your two sound a lot like my two.
they are siblings as well as yours. when they were babies, they shared a cage, though they bickered from time to time... but they often paced their cages when i separated them. however, one day our female decided that she didnt like her brother in the cage anymore and she'd attack him any chance she got. she tried to kill him over a bowl of veggies, giving him a nasty bite to his leg. after that, they no longer ever shared a cage. they started growing apart around 6-8 months old, when the hormones first started setting in.
biting, what are you doing when you get bit? lovebirds are cage territorial and all nip to some extent. even my male nips when i enter his cage to move toys around, feed, water, etc. my female used to bite and she'd latch on and not let go lol but since taming her, she rarely bites bad. not unless i enter her cage without petting her first lol
in my experience, separating my two was the best choice, for their own safety because the bickering grew worse and worse, though they cuddled and played together as well.
you can try a few things. either give them a totally new very large cage where they can get away from eachother if they need to, or you can separate them.
mine no longer can see eachother, i have to block their view from eachother or the flock calling is horrendous (husband works midnights during the week, i work midnights on weekends so we cant really have that) and they pace and pace and pace. plus our female gets hormonal when she sees our male.
depending on their age (4-8 months i found to be where they start hitting maturity) i found mine to go through a very nippy stage where they were more inclined to bite more often. this can be trained out of them, and its easier if your two are tame.
my female was handraised from day 1, as she was the runt of her clutch and trampled by her siblings, however she was not properly socialized so she wasnt "tame" per se when we got her and her brother. her brother was parent raised plus he has a timid personality. he isnt fully tame, but he is just not people oriented like his sister is. munch is fully tame now, she's just fiesty and she rules the roost and she knows it. we worked out a compromise with her as we found out when and why she bites.
she bites in her cage. she doesnt like us in her cage without her permission. she will bite us if we invade. however, if we open the door, let her come to us and she sits in the cage door and demands that we pet her and give her kisses. if we do, then she lets us do whatever in her cage and she's totally fine with it. that's our strange compromise lol we pet her first, then go in her cage. she's quite manipulative haha.
what im getting at is for you to find out WHY your two are biting you, and for you to find a way to avoid it. all birds bite for a reason. sometimes you just have to dig deep. usually, its the human's fault you get bit.