First of all I should state, that I didn’t work with Belarus Records. Maybe Belarus is different.
Therefore, I’m not sure if I will confuse the issue or my email will answer some of the concerns re: Double Surnames.
In my far too many encounters into Archival Records, I’ve met with the following statements...Yankel (let’s say) Goldberg and then (either in brackets or not) the following is written also known as such & such, where completely different surname is added to the record.
Hope it helps.