Thank you for your post, and I apologize for the late reply.
I am working with FileMaker Pro Advanced 10 on my iMac with OS X 10.5.7. I am unable to duplicate the problem. This is what I have done:
1. I created a new database file, Test.fp7, with one text field, Name, with storage for 10 repetitions. My layout shows the ten repetitions horizontally.
2. I created a second database file, Test1.fp7, with one text field, Name, with storage for 10 repetitions. I removed field from the layout.
3. The table name for Test1.fp7 is named Test1. I renamed it to Test.
4. I returned to Test.fp7, went to Layout mode, selected the repeating Name field and copied it to the clipboard.
5. I switched to Test1.fp7, went into Layout mode and pasted. The Name field was pasted, with all ten repetitions, horizontally.
Please let me know what I have done differently than you, and I'll try to duplicate the problem.