Please help- male babies fighting!

Hello everyone. Need advice, suggestions and thoughts. I have 2 male conures, 6 months and 3 months- both male. The 3 month old is the new addition to our house and after a quarantine and vet check-up was introduced to my older male. Separate cages but supervised playtime in neutral territory. Half the time all is great- mutual preening, cuddling, food sharing and my older male even tries to regurgitate and feed the baby. The other half is not so great- not sure if I'd call it beaking or fighting as I'm unclear of the difference- but nonetheless, I intervene quickly so no one gets hurt. they are going at each other with their beaks while making these awful noises, feathers ruffled, tailed fanned out and neither back off. What is going on here? I understand they may never be buddies, but after days of lovey sessions of preening and feeding, there are days they can't be out together as they immediately go after the other and start fighting.
Please offer any insight and advice on helping with their interactions. Thank you.

Hard to say without seeing a video what they're up to. My guess is that they're just working out their pecking order. If it was a "real fight" there would be feathers flying, loud yelling, and there would be no doubt about it.

Raven and Griffin are good friends, but they have squabbles a lot. I noticed that if I don't separate them, one will eventually "lose" by getting pushed off the edge of the perch, or getting knocked off the rope, etc. If it goes on for too long I will separate them since there's a significant size difference with these two, but I'm not as worried about it as I used to be.

Since you've seen your birds preen each other and be buddies at other times, they should be fine. It's pretty normal I think.

My two conures will "fight" and wrestle.. they never REALLY hurt each other, though. They make their sounds and they sure do make a ruckus, but I've never been worried about them being together. They've never pulled feathers/drawn blood/etc on each other.

Hmmm. Thanks for your thoughts. I do think they're fighting just based on the fact that they stand tall, get really fluffy and charge each other. It's hard to say that if left alone they would hurt each other, as I have always separated them once I felt uneasy about the situation. It is hard separating them at times. Same scenario as yours??

Like RG & Sterling have said I'd bet on playing and/or establishing a pecking order.....if they were seriously fighting, one or both would have broken and/or pulled out feathers, maybe a chewed off toe or other evidence of blood.....birds that want to do harm to each other are not going to eat together and sit together.....there probably is a way to find out yourself, don't put them in their own cages tomorrow night, feed & water them on top of one of the cages, or even in some other neutral location, then watch where they end up sleeping...if the sleep together, they're friends.....

Now I'm curious to see a video of the occurrence! Seriously, if birds truly wanted to fight there would be blood/toes bitten off, feathers everywhere, etc. and they wouldn't be friendly with each other. I've never heard of birds who were "friends" try and fight to the death at other times. Doesn't make sense for animals.

My conure (the first bird) started fighting with the new lovebird and budgies I got, but I have had enough time and patience to train them not to fight. He was about 5-6 mo old when I got the other birds. I'm not very good at training, but that's a must for all of my birds - no fighting is allowed ever. Now I can keep them all in one cage unattended for hours and they never even get aggressive…
They CAN learn not to fight - you just have to be very consistent with that. And make sure they are in separate cages for now and let them be together only when you supervise.
As many others said here they might be just playing - not fighting seriously. But my conure got really mad - he puffed up and his eyes went wild, so I knew it wasn't a game. But luckily he is a very obedient boy, and I haven't seen him trying to fight for months. I hope he just got used to the new birds, and now he really loves them all.

Thank you all for the helpful advice. Along with my son I'm going to try and take a video of what leads to their confrontation and what it looks like when they start fighting. Hopefully that will give you all a little bit more insight.
Honestly, just by the fact that they do get all puffed up, their tails flare out and their eyes get wild I do think they both have intentions of fighting. Sometimes when I try and break up their little altercations I get bit in the process. They have yet to hurt each other but I'm afraid if I don't intervene that they might. I will keep their interactions out of their cages to a minimum because I don't want to stress them out too much since they do seem tense with each other. It's so confusing considering they had a good week and a half of great bonding and preening and feeding.
They do have their own cages and are only out when I'm around them supervised.