And this is where the problem of those new pets comes up.
Most of those new pets are pretty useless imo. But pets like Auraio (Teambonus for 4 green troops, which is kinda helpful in guild wars) will show up less often.
My solution would be: Let those troop-related pets only show up once you upgraded the adjecent troop to gold.
Or change the petrescue system completely by spawning another pet if the current pet rescue would be for one you already have maxed out.