You don't need to get exactly the same spec batteries.
For example, the 1000 mAH refers to how much charge the batteries hold - the higher the better, so if you want the batteries to last longer, go for 2000+ mAH.
Just make sure though, that all the batteries have the same mAH rating, otherwise, it is possible that one lesser mAH battery will drain before the others, causing extra strain on the remaining batteries or causing the device to not work until all batteries are replaced.