richar babcock The answer is No. Listen to littleriverphil and stallzer -- they are absolutely correct. Off cover the Sc# 300 the used stamps shown on your covers are virtually worthless. Now, consider this…
The Treasury "Penalty" cover is an interesting usage. The government employee did not follow procedure in mailing this cover; it was used for "Private" purpose, based on the pair of the Sc# 300s. Government employees were allowed to use "Penalty Envelopes" for "Private Mailing" providing they paid for all postage and covered the indicia in the upper left corner card reading, "OFFICIAL BUSINESS - Penalty For Private Usage $300". This is a good item and something that would end-up in an exhibit of Sc#300 Postal History, Treasury Department Postal History and Penalty Envelope Postal History, etc.
So, this is why you avoid soaking stamps off covers.

Happy Holidays!
Hal