24" dia pot may be too big to start when planting roses that are currently in a band size pot. You may what to first start them off in a 1 or 2 gal pot.

Which minis do you have and how deep is the pot? As that would make a difference on if you could eventually plant them both in the same pot.

I don't see a problem with that... I planted 6 minis in a window box and would transplant them when they got too big...

I have planted my Vi's Violet and Baby Boomer together in a pot that is about 1 1/2 gallons. Just put them in yesterday, watered well. They are sitting in partial shade on the balcony. Hoping the weather here will last into Oct/Nov since we've had such a cool summer. It is Chicago though and that may just be wishful thinking but I'm hoping to get some good growth going before the frost begins.

Kforrest

Even if these are fresh out of the band pot minis, a 1 1/2 gal pot is really small for two plants. IMO, would recommend stepping up to a larger pot so they have room to grow.