I think it is impossible that all 3 are authentic.
Of course at least two of the identical coins must be casts, probably all three. But these are not "
Bulgarian imitations", which implies not modern casts, but modern dies manufactured recently in
Bulgaria.
The dies of the original coin from which the casts were made were authentic, as shown by other clearly authentic specimens from the same dies, Varbanov's, mine, and doubtless others.