@Saimonas Balinskas, Thanks for posting in Q&A.
From your description, I know you want to know whether Multiple Apple Business Manager accounts is possible for one single tenant.
Based on my research, it is possible to have Multiple Apple Business Manager accounts in one tenant and there is some useful information you can refer in the following link.
https://www.reddit.com/r/Intune/comments/18550fr/can_you_have_multiple_apple_business_manager/
Non-official, just for reference.
Hope it will help.
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