Cal from U.S.

I recently purchased an 1887 Victoria Jubilee gold half sovereign. I believe it's genuine since it's slabbed and certified AU58 by CCCS. I confirmed the certification number in their database. What I can't identify is an imperfect "J" in the initials. The expected J.E.B. clearly appears as I.E.B. I've read of this on some full sovereign varieties from Melbourne and Sidney mints, but there's no reference to I.E.B. initials on a half sovereign, and my coin has no mint mark so it came from London. There's no mention of this in Spink. Except for the I.E.B. initials, my coin appears to be a Spink 3869. Does anyone know if this is an unknown or unmentioned variety?