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Yeah, it's confusing. From what I was able to learn: RDNA is the ROMAD token which was distributed through the personal cabinet on the site (you can call it the main one). RBDN is a token that was distributed through the CLET platform as an airdrop. It turns out that these are the same tokens.
We can say tokens of two different bounty campaigns.
Your explanation disorients me even more. This is the same token, but different companies

It must be simple to exchange RDNA to RBDN. As I understand the price of the tokens on exchanges will be different.