Here are a few Lapco Piggybacks which I will be listing in the week to come with a few other lapco parts.
These brackets can be used to mount either two bottles as seen in the scan from Paintball Magazine (October 1992) or used to mount a duckbill asa under a T stock.
The tanks are typically set up with on off valves so air is not lost.
Find this post on facebook at:
https://www.facebook.com/photo.php?fbid=335096029917712