Odd timing mark tab..

So I decided to detail the 200 engine in my '66 Mustang.
Stripped all the bits and parts off the block. Discovered the timing tab is bolted to the timing cover so I remove that.
Under the tab is the timing marks cast into the timing cover. From what I can tell the numbers and the position of the marks are the same.....

Any reason for this?

There are 23 years of small Ford I6. Not all timing covers had the casting marks. The ones with the casting marks didn't have tangs...usually!!

The bolts held other ancillary devices, so the tang could get removed. IIRC, some dealer fitted York compressors for A/C used long custom made metal strips to hold the units, while factory ones used special mounts.