MIflyer, you are correct in saying that the Altimeter has one hand , but I fear it has been "played with" as 6A/1538 is a 3 pointer sensitive altimeter.
I believe it could be a modification ,removing 2 smaller pointers and painting the red "danger" band for recreational parachuting purposes.
This appears to be a common mod. (ie Not the only one I have seen .)Perhaps someone in the Sky Diving community could confirm or otherwise.
Regards Mike