There are various 2 rounds holders on the market that range from sewn elastic loops from SAP to fully machined version from Hoptic. This new version from Inflection appears to split the difference nicely between the two.
SAP: https://www.shortactionprecision.com/products/sap-two-round-holder
InflectionDE: https://www.inflectionde.com/product-page/os-ammo-caddy
Hoptic: https://www.hopticusa.com/product-page/quiver-with-velcro-adapter
SAP: https://www.shortactionprecision.com/products/sap-two-round-holder
InflectionDE: https://www.inflectionde.com/product-page/os-ammo-caddy
Hoptic: https://www.hopticusa.com/product-page/quiver-with-velcro-adapter