I bet you didn’t realize what paparazzi-junkies the Thumbs were. Charles Stratton and Lavinia Warren were frequently photographed, throughout their life. I don’t know if they profited from the sale of their photographs or not – I would hope they did, but given the general state of intellectual property ethics in the later half of the 19th century, I highly doubt it. Often the photographers themselves didn’t, as others would buy one copy of their image, re-photograph it and sell it themselves at a cheaper price!

Here they are, at middle age, in an anonymous CDV. I think this may be a copy of someone else’s photo, although if it is it’s a very good one, because it has no photographer’s stamp on the verso (and because it is such a good image, it strikes me as odd that there is no stamp taking credit).
In doing some more digging around, I found another copy of the same image. This one had a stamp on the bac from the photographer – a K(?).C. ????, Photographs and Ferrotypes, ??? Main Street, Bridgeport, CT. The Thumbs resided in Connecticut in their later years, so this is entirely reasonable.

Also, the blotchy mottling at the margins of the image is present in both copies, so I assume it is actually in the original negative, which is a relief.
PT Barnum lived in Bridgeport, and I believe both Thumb and Barnum are buried in the same Bridgeport cemetery.