RE: Strange ? If you bought your shares that were settled on two different dates, or with a different broker, it is possible they are sending you proxies for each set of those.
I imagine with a lot of us having averaged and accumulated our shares over a period of time, this may be the case. So far I have only received one set of yellow and green proxies. I have casted my vote for the yellow, and am archiving the green one for fun.