I had to use 2 Dynaplugs for a puncture. The first Dynaplug allowed some leakage. The second one sealed the puncture. Maybe it was because of the size of the puncture (I think it was) because I've used single Dynaplugs on car tire punctures effectively. Anyway, the double Dynaplugs lasted maybe 4-5k miles with no issues. I saw the plugs intact when my rear tire was eventually replaced 2 weeks ago. I have confidence in Dynaplugs. BTW, Dynaplug did mention that you can use multiple plugs on larger punctures.
Shaolin Master Sergeant
2013 K1600 GTL Dark Graphite Metallic