Thanks to Ranok and others for their replies, this helps a great deal, but will just clarify again the issue I had, now resolved:-
I use the auctionator addon , and usually use the buy type, which allows me to search for a specific item at the lowest price.
As I searched for sunreaver micro sentry it did not show the 1/3 next to the ones for sale, yet did show the 1/3 for iron starlette.
I am looking to add some duplicates such as the sentry to my collection, plus a few others for pets I really enjoy , example nexus whelplings, love how 2 of these on 90% of battles can destroy Jahan, Samm, and Archimedes, so that any pet with over 234 health can belevelled fast.
Appreciate the assistance and prompt replies, will be adding pets from ah to be duplicates and triplicates now I can refer to Ranok's list.