Incredible 2 -> Bionic & Incredible 2 repurpose

[smccloud]

I currently have an Incredible 2 and I'll be getting a free Bionic when the Galaxy Nexus comes out. At the same time, my Incredible 2 will goto my sister-in-law to replace her Curve 8330. Do I need to get a new SIM for both phones or just the Bionic?