The below used Jamaica 307 (SG 308) is from an auction lot that I bought from the UK. It is marked as a variety with added purple on flower. I don't see that list anywhere. I don't see this color on any of the other ten or so stamps of this issue in the lot. Is it an ink smear or a genuine error? Is there a Jamaica or West Indies specialist catalog that might list it. Thoughts?

Thank you in advance.
Bill