Australian 20 Cent 2001 Mint mark question.

for 2001 20 cent https://en.numista.com/catalogue/pieces1702.html
there are list IRB spaced, IRB joined, and RB joined.

I'm pretty sure both of these coins are RB joined (but I'm willing to be corrected) however the 2nd picture I have questions about. The first I consider 'normal'


the 2nd I don't know what to call this. Double punched? raised? is this an error? or common place? anything special about it?

Looks very much like a double die to me.

It is not a Mintmark, just the Designers initials. Definitely an RB joined but yes it is unusual with that doubling. I haven't seen that on a 20 cent before.

Mike