I would and have. You can see the week and year made on the side. As long as there is no major cutting etc where they have been on and off or puncture repairs, you should be OK - oh and not too old.
Stick to a martching pair and you should be right.
I've bought bikes with mis-matched and / or out of date tyres, which I feel is worse. but it is down to you, there are tyre shop sellers on ebay, just choose carefully from those who seem to know what they are selling.
My 2p worth.
Saying that, my Fazer (bought this week) has Maxxis tyres on which I would never have chosen, but it feels fine, flops from side to side easily and I leant over further in the wet the other morning than I think I have for ages, that being on a bike I am getting used to. They are cheap enogh new, so maybe another option. get a new front the same later on.