It would appear that there were (maybe are) 2 10-dia bar brooches - one for QV and one gifted to QM.
There is plenty of evidence that QV's 10-Dia brooch was used by QV, QA and QEQM. [Granted this is from photographic evidence and accounts - without inspecting each wearing we cannot be 100% sure]
We have no photographic proof however that the 10-dia brooch of QM has ever been WORN.
I think that there was some speculation in the previous thread that the 10-dia gift may have been altered to create the 14-dia bar used by QM (and subsequently by QEII).