What game? Matching dice with two each of d4, d6, d8, and d10
Ah-ha. I searched for the 2015 gen con convention map, looked up the booth number and found the associated store.

Lumps, by Continuum Games There are a couple of printings, with various packaging and dice colorings (I'm a bit partial to the coal-colored ones).

https://continuumgames.com/shop/lumps-non-seasonal-edition/

As mentioned in the question, a matched pair gives the face-value of those dice, with additional matching dice increasing the total by the face-value again (two 2s are two points, three 2s are four points, etc). First player to 100 points wins.

Later printings include additional rules, such as a solitaire mode, which is just a race to 100 points; a hard mode where you have to set aside dice every roll  instead of banking on the last roll to save you, and some other quirky optional rules, such as all even numbers granting a bonus (or odd numbers).