iphoto deleting duplicates

i think there my be one or possibly even 2 copies/duplicates of multiple photos in my iphoto. is there some way of telling my macbook/iphoto to delete all duplicate (or triplicate) photos in my library and keep only the original (one set of original) photos?

i think the duplicate photos are eating up a lot of space on my computer and contributing to the "start up disk is almost full/delete files".

trying to find the duplicate photos one by one and deleting them seems way too cumbersome. there must be an easier/faster way that i am just not aware of.


thanks for your help,
anthony