Those are two different varieties with very similar names. The first is Peaches & Cream, a light blend waterlily that does very poorly in competition and can be found at many big box stores in spring. The second is Peaches-N-Cream, an orange and white bicolor formal decorative that does very well in competition and tends to have touchy tubers for experienced growers I have talked to about it.

It is possible, I suppose, to find Peaches-N-Cream in normal stores, but much more likely that it would be the first Peaches & Cream.

If you are hunting down either variety, check out this link for dedicated suppliers focused on dahlias- http://www.dahliaaddict.com/search.php?alpha=p