fix(spec-specs): duplicate storage writes in state tracker (ethereum#1743)

- Perform a similar check to balance changes and other
  tracker methods and keep only the last write.

Author: fselmo

docs/CHANGELOG.md

@@ -22,6 +22,7 @@ Test fixtures for use by clients are available for each release on the [Github r
 ### 📋 Misc
 
 - 🐞 WELDed the EEST tox environments relevant to producing documentation into EELS, and added a tool to cleanly add codespell whitelist entries. ([#1695](https://github.com/ethereum/execution-specs/pull/1659)).
+- 🐞 Fix duplicate storage write issues for block access lists EIP-7928 implementation ([#1743](https://github.com/ethereum/execution-specs/pull/1743)).
 
 ### 🧪 Test Cases
 

src/ethereum/forks/amsterdam/block_access_lists/builder.py

@@ -126,8 +126,8 @@ def add_storage_write(
     Add a storage write operation to the block access list.
 
     Records a storage slot modification for a given address at a specific
-    transaction index. Multiple writes to the same slot are tracked
-    separately, maintaining the order and transaction index of each change.
+    transaction index. If multiple writes occur to the same slot within the
+    same transaction (same block_access_index), only the final value is kept.
 
     Parameters
     ----------
@@ -149,6 +149,18 @@ def add_storage_write(
     if slot not in builder.accounts[address].storage_changes:
         builder.accounts[address].storage_changes[slot] = []
 
+    # Check if there's already an entry with the same block_access_index
+    # If so, update it with the new value, keeping only the final write
+    changes = builder.accounts[address].storage_changes[slot]
+    for i, existing_change in enumerate(changes):
+        if existing_change.block_access_index == block_access_index:
+            # Update the existing entry with the new value
+            changes[i] = StorageChange(
+                block_access_index=block_access_index, new_value=new_value
+            )
+            return
+
+    # No existing entry found, append new change
     change = StorageChange(
         block_access_index=block_access_index, new_value=new_value
     )