So.... after some searching I found the trace values required to determine whether client side dedupe is working for the SQL TDP.

I launched the trace and reviewed the log but am a little cloudy on the returned values. If you are handy with this type of thing please let me know what i'm looking at here:

This was a full TDP backup of a 319GB database with compression and client side dedupe enabled:

tsmEndSendObjEx: Total bytes send 0 11456, encryptType is NO encryptAlg is NONE compress is 1, dedup is 1, totalCompress is 0 2308 totalLFBytesSent 0 0 totalDedupSize 0 11456 txnBytes 11456

tsmEndSendObjEx: Total bytes send 38 1908852224, encryptType is NO encryptAlg is NONE compress is 1, dedup is 1, totalCompress is 8 75125156 totalLFBytesSent 0 0 totalDedupSize 38 1908852224 txnBytes 165117609472

tsmEndSendObjEx: Total bytes send 40 2886070784, encryptType is NO encryptAlg is NONE compress is 1, dedup is 1, totalCompress is 8 2077368466 totalLFBytesSent 0 0 totalDedupSize 40 2886070784 txnBytes 174684762624