Well, sites always say "Never house two snakes together" but plenty of folks do that without any issues too.

I think using pine(kiln dried preferably) isn't like housing two snakes together really. I mean, commercial breeders used pine bedding for how many years? So while it might be as good as aspen, I don't think it's a 'death sentance' automatically either.

I use the aspen myself. I don't like the smell of the pine bedding. Both are from renewable resources. The aspen mulches better than the pine.