do my guinea pigs need seperating?

Question
i have two male Guinea pigs who are roughly the same age( i think 6 months). Pudding and Biscuit. We brought Pudding as a companion for Biscuit, we paired them together because they got along well at a adoption center. They've allways got along great before.

Recently, while i was cleaning their cage i saw them acting differently. They'd make a weird almost vibrating noise and kind of shake their hips and chase each other for a minute, then they'd go back to normal. I've seen this happen a few times. Is this okay for them to be doing? are they just sorting out dominance, then will be okay to live together?  i separated them because i saw Biscuit had a small scratch on his nose and i didn't want them to hurt each other.

Are they safe to keep together or do i need to seperate them?

sorry if you've answered this before
PS they live in fairly big two story cage in the garden.  

Answer
Male guinea pigs make this rumbling sound in territorial disputes and also a similar sound is used around females when courting. This behavior is apparent around 5-6 months when they are at their peak to start breeding.
If they are drawing blood then they will have to be separated. It is worth while getting them neutered as they may get on better once testosterone levels have dispersed.
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