I've considered doing that myself, but decided not to. Two possible issues.
1- it might increase the width at the base of the valve and cause seating problems on narrow rims.
2- it might hold the stem too high, and cause the tube to tear as it stretches around the ring and down to the rim next to it.
I'm disappointed in the way tube makers got rid of the base flange on valves to accommodate narrow rims, but gave too little thought to how weak the tube/valve joint is. I see more tubes torn at the valve than ever. For my own use, I now use a hole punch on a featheredge patch and add it as reinforcement on all the new tubes for my commuter.
Other than that, I suggest staying with only the one ring, but leaving it loose. It'll still work as a stop when you fit the pump, but is maybe (hopefully) less likely to cause a failure at the base of the valve.
__________________
FB
Chain-L site
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