Hello Paul Filkin ,
Thanks.
Ops....no I did not retain a copy of the original translation memory. (goofed-up) But not to worry...another copy exists.

Some context:
a) there were some 58,000 units in the TM (size shown presently is 906 MB) -- original
b) the new TM has about 24,000 units in the TM (size is 464 KB) -- after batch delete and Upgrade

This is how I deleted the duplicates:
a) Deleted individual units ...by searching for them.
b) Did a batch edit with a filter. Filter was find source and target segments with <cf size=. Lots of segments with such codes were present in both the Source and the Target.

Batch edit took about 2 hours. I got the message that 23, 456 segments were deleted.

I wanted to sort of clean up the new TM. I thought Upgrade translation would do it. I ran the Upgrade Translation.

When I opened either of the TM...the original or the new "upgraded" one....there are no translation units in them as per the setting.

Many thanks for your help.

Guru