You get hugely more creosote buildup in single wall flue
This.
Yes, you can get creosote in single/double/triple. The double/triple will maintain their internal (high) temp better/get less condensation/develop MUCH less creosote. Also, if you DO get a chimney fire, the extra walls should help in that respect as well (keep the outer wall from getting hot as quickly).
Do as you wish, but chimney fires are REAL and can be disastrous.
