At the end of port's build there is a report listing duplicate files:
Duplicates 30718 bytes (29407 compressed):
Duplicates 81660 bytes (79986 compressed):
Duplicates 188680 bytes:
WARNING: Found 128 duplicated files taking 558556 bytes (529181 compressed)
Either some of these aren't needed at all, or, if different parts of the software do expect to find the same things under different names, they should be installed as hardlinks, not copies...
www/seamonkey has been removed in ports r505753