diff --git a/packages/crypto/src/errors.ts b/packages/crypto/src/errors.ts
index dae91513ba..d5e48a797f 100644
--- a/packages/crypto/src/errors.ts
+++ b/packages/crypto/src/errors.ts
@@ -106,6 +106,12 @@ export class TransactionAlreadyRegisteredError extends CryptoError {
     }
 }
 
+export class TransactionKeyAlreadyRegisteredError extends CryptoError {
+    constructor(name: string) {
+        super(`Transaction key ${name} is already registered.`);
+    }
+}
+
 export class CoreTransactionTypeGroupImmutableError extends CryptoError {
     constructor() {
         super(`The Core transaction type group is immutable.`);
diff --git a/packages/crypto/src/transactions/registry.ts b/packages/crypto/src/transactions/registry.ts
index aeba936029..5ce228c8ce 100644
--- a/packages/crypto/src/transactions/registry.ts
+++ b/packages/crypto/src/transactions/registry.ts
@@ -2,6 +2,7 @@ import { TransactionTypeGroup } from "../enums";
 import {
     CoreTransactionTypeGroupImmutableError,
     TransactionAlreadyRegisteredError,
+    TransactionKeyAlreadyRegisteredError,
     UnkownTransactionError,
 } from "../errors";
 import { validator } from "../validation";
@@ -60,6 +61,10 @@ class TransactionRegistry {
             throw new TransactionAlreadyRegisteredError(constructor.name);
         }
 
+        if (Array.from(this.transactionTypes.values()).some(({ key }) => key === constructor.key)) {
+            throw new TransactionKeyAlreadyRegisteredError(constructor.key);
+        }
+
         this.transactionTypes.set(internalType, constructor);
         this.updateSchemas(constructor);
     }