Doug,
That's a good thought, but it doesn't explain what I see, since the copy
comes out clean if I select "Match Destination Formatting" in the Paste
Options pulldown. I'm also familiar with templates, and I have no sheet.xlt
(this is on my machine, and I've never set a sheet template). I know the
problem is linked to the source formatting somehow, but I don't understand
how. I can cleanly copy into the new workbook from several other files I've
tried, even after the strange copy from my original workbook. After the
first copy/paste from the "trouble" file, all copies from that file show up
this way, but no copy/paste from any other file I've tried does this, and
sequence of doing these copies has no effect.

Obviously, fixing this is nothing more than a nuisance, but I wish I knew
the cause.