diff --git a/programs/config/src/config_processor.rs b/programs/config/src/config_processor.rs
index d93ed85ac57eaa..09743d38c35357 100644
--- a/programs/config/src/config_processor.rs
+++ b/programs/config/src/config_processor.rs
@@ -11,6 +11,7 @@ use solana_sdk::{
     program_utils::limited_deserialize,
     pubkey::Pubkey,
 };
+use std::collections::BTreeSet;
 
 pub fn process_instruction(
     _program_id: &Pubkey,
@@ -101,6 +102,15 @@ pub fn process_instruction(
         }
     }
 
+    if invoke_context.is_feature_active(&feature_set::dedupe_config_program_signers::id()) {
+        let total_new_keys = key_list.keys.len();
+        let unique_new_keys = key_list.keys.into_iter().collect::<BTreeSet<_>>();
+        if unique_new_keys.len() != total_new_keys {
+            ic_msg!(invoke_context, "new config contains duplicate keys");
+            return Err(InstructionError::InvalidArgument);
+        }
+    }
+
     // Check for Config data signers not present in incoming account update
     if current_signer_keys.len() > counter {
         ic_msg!(
@@ -493,6 +503,96 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_config_initialize_contains_duplicates_fails() {
+        solana_logger::setup();
+        let config_address = Pubkey::new_unique();
+        let signer0_pubkey = Pubkey::new_unique();
+        let signer0_account = RefCell::new(AccountSharedData::default());
+        let keys = vec![
+            (config_address, false),
+            (signer0_pubkey, true),
+            (signer0_pubkey, true),
+        ];
+        let (config_keypair, config_account) = create_config_account(keys.clone());
+        let config_pubkey = config_keypair.pubkey();
+        let my_config = MyConfig::new(42);
+
+        // Attempt initialization with duplicate signer inputs
+        let instruction = config_instruction::store(&config_pubkey, true, keys, &my_config);
+        let accounts = vec![
+            (true, false, &config_pubkey, &config_account),
+            (true, false, &signer0_pubkey, &signer0_account),
+            (true, false, &signer0_pubkey, &signer0_account),
+        ];
+        let keyed_accounts = create_keyed_accounts_unified(&accounts);
+        assert_eq!(
+            process_instruction(
+                &id(),
+                &instruction.data,
+                &mut MockInvokeContext::new(keyed_accounts)
+            ),
+            Err(InstructionError::InvalidArgument),
+        );
+    }
+
+    #[test]
+    fn test_config_update_contains_duplicates_fails() {
+        solana_logger::setup();
+        let config_address = Pubkey::new_unique();
+        let signer0_pubkey = Pubkey::new_unique();
+        let signer1_pubkey = Pubkey::new_unique();
+        let signer0_account = RefCell::new(AccountSharedData::default());
+        let signer1_account = RefCell::new(AccountSharedData::default());
+        let keys = vec![
+            (config_address, false),
+            (signer0_pubkey, true),
+            (signer1_pubkey, true),
+        ];
+        let (config_keypair, config_account) = create_config_account(keys.clone());
+        let config_pubkey = config_keypair.pubkey();
+        let my_config = MyConfig::new(42);
+
+        let instruction = config_instruction::store(&config_pubkey, true, keys, &my_config);
+        let accounts = vec![
+            (true, false, &config_pubkey, &config_account),
+            (true, false, &signer0_pubkey, &signer0_account),
+            (true, false, &signer1_pubkey, &signer1_account),
+        ];
+        let keyed_accounts = create_keyed_accounts_unified(&accounts);
+        assert_eq!(
+            process_instruction(
+                &id(),
+                &instruction.data,
+                &mut MockInvokeContext::new(keyed_accounts)
+            ),
+            Ok(()),
+        );
+
+        // Attempt update with duplicate signer inputs
+        let new_config = MyConfig::new(84);
+        let dupe_keys = vec![
+            (config_address, false),
+            (signer0_pubkey, true),
+            (signer0_pubkey, true),
+        ];
+        let instruction = config_instruction::store(&config_pubkey, false, dupe_keys, &new_config);
+        let accounts = vec![
+            (false, false, &config_pubkey, &config_account),
+            (true, false, &signer0_pubkey, &signer0_account),
+            (true, false, &signer0_pubkey, &signer0_account),
+        ];
+        let keyed_accounts = create_keyed_accounts_unified(&accounts);
+        assert_eq!(
+            process_instruction(
+                &id(),
+                &instruction.data,
+                &mut MockInvokeContext::new(keyed_accounts)
+            ),
+            Err(InstructionError::InvalidArgument),
+        );
+    }
+
     #[test]
     fn test_config_updates_requiring_config() {
         solana_logger::setup();
diff --git a/sdk/src/feature_set.rs b/sdk/src/feature_set.rs
index f6cf3f90671043..d7f9eda10f3c87 100644
--- a/sdk/src/feature_set.rs
+++ b/sdk/src/feature_set.rs
@@ -147,6 +147,10 @@ pub mod system_transfer_zero_check {
     solana_sdk::declare_id!("BrTR9hzw4WBGFP65AJMbpAo64DcA3U6jdPSga9fMV5cS");
 }
 
+pub mod dedupe_config_program_signers {
+    solana_sdk::declare_id!("8kEuAshXLsgkUEdcFVLqrjCGGHVWFW99ZZpxvAzzMtBp");
+}
+
 lazy_static! {
     /// Map of feature identifiers to user-visible description
     pub static ref FEATURE_NAMES: HashMap<Pubkey, &'static str> = [
@@ -184,6 +188,7 @@ lazy_static! {
         (memory_ops_syscalls::id(), "add syscalls for memory operations"),
         (add_missing_program_error_mappings::id(), "add missing program error mappings"),
         (system_transfer_zero_check::id(), "perform all checks for transfers of 0 lamports"),
+        (dedupe_config_program_signers::id(), "dedupe config program signers"),
         /*************** ADD NEW FEATURES HERE ***************/
     ]
     .iter()