you are allowed to muti-rebate. just because you find it cheaper elsewhere and have a coupon code doesn't mean that you have to forfeit your rebate. I work for staples and it's been done. But the 110% pricematch policy is not accurate on what it was listed. Staples will pricematch competitors 100% if u come in store and buy it. Staples will price match a competitor 110% if u already bought the item and then find it cheaper elsewhere. atleast that is how the policy is suppose to be, some people (even associates) don't even know (just a fair warning if you don't get the 110% pricematch)
you can try to pricematch the unpopular places, like stores that aren't even advertised on tv and such. staples is being more strict on pricematching. "We WILL price match our major competitors." ie. best buy, office max, office depot, compusa, and etc. you are always welcomed to try. but it it really does depend on the associate that is checking you out.
but anyways keep up the scouting!