[UK-CONTEST] Station giving conflicting callsigns on Club Calls Contest - penalty?

[Michael Ruttenberg G7TWC]

Anyone else notice that G6UW was alternating their callsign with GX6UW?

The question really is is there any penalty for anyone who worked them under (say) G6UW whereas someone else logs it as GX6UW? Who is said to be correct when the station wasn't consistent in sending their callsign? I'd hate to think some ops losing points because of a busted call when it was just what they were sent at the time.

Mike
G7TWC