G is definitely capable to recognize that is the same picture, not sure if it can do it if we are talking about resized picture, but....
1) This can't have a big seo score and I'm sure you have many others, more important, things that you should fix.
2) It will leave a bad impression for your visitors, no matter what is your final goal the visitors is what you are looking for.
To make it short use 10 pictures since is not the end of the world to find 10 suitable picture and in the worst case you can pay $10-$12 for some custom ones.