Thank you for the post.
I am able to reproduce this on Mac OS X 10.7.5 with FileMaker Pro 12.0v4. On Windows 7, I was not able to reproduce, the colors pasted into the container field appeared to be identical to the box's fill.
The results of my test on Mac OS X 10.7.5 follow:
Box # 1 Original Color: Red 255, Green 0, Blue 0
Box #1 Pasted Color: Red 252, Green 13, Blue 27
Box #2 Original Color: Red 0, Green 255, Blue 0
Box #2 Pasted Color: Red 41, Green 253, Blue 46
Box #3 Original Color: Red 0, Green 0, Blue 255
Box #3 Pasted Color: Red 11, Green 36, Blue 251
Box #4 Original Color: Red 0, Green 0, Blue 130
Box #4 Pasted Color: Red 2, Green 13, Blue 128
Box #5 Original Color: Red 130, Green 0, Blue 0
Box #5 Pasted Color: Red 128, Green 3, Blue 8
I forwarded a full report to Testing and Development for review.
I've added an entry on this in the Known Bugs List that links to this thread. I currently list the issue as "mac only" but if TSFalcon revisists this with info that he could reproduce the issue in windows, I'll update accordingly. Please do not post comments about this issue to the known bugs list. Post them here instead.