I had an Achilles with 2 Idols for almost 10 years, prior to Katrina. Of course, one example doesn't mean anything; but there's nothing I know of that would be a problem. Probably some pecking order stuff. If the Idol doesn't go in first, I'd put the Achillies in your QT when the Idol comes out. Give the Idol a couple of weeks to establish himself and start eating, then re-introduce the tang.