Mixing pumped milk?

I've been breastfeeding my 8wo and introduced an occasional bottle a few weeks ago. I've recently stepped up pumping to 1-2 times per day mainly due to the fact that my son sleeps much longer hours st night and my breasts get so full he can't latch and also to have some milk for freedom to let my husband feed. My question is can I mix milk that's been pumped at different times? For example, I pumped 5oz the other morning and that's more than my son will drink at one time. Can I mix the extra ounce with another smaller bag of milk I've pumped? May be a dumb question but im pretty new to pumping and bottle feeding