Is there a way to search my multiplant images to be sure I am not adding a duplicate ?

Yes, go to your Profile page and under 'Plant Database Contributions' you will find your multiplant pics.

I guess I needed to clarify. I meant , Is there a "search" for my multiplant images.
In other words if I "search" African Queen, will the search find that multiplant ?
If the search doesn't find the plant I would assume I havn't posted a multiplant image containing that lily.

I see, no I don't think you can find them like that, only if you go to the entry of that particular variety of African Queen in the database.
Maybe someone else knows more..

I think bonitin is right. I just looked at my meager collection of Multiplant photos and it appears that the only way to see what plants are tagged is to click on the photo. But if you have submitted a Multiplant with a particular plant tagged, it will show up in the entries for that plant in the database. So probably the easiest way to avoid duplicates is to check the database entries for the plants in the photo you're contemplating adding. (Did that make any sense at all? )