That was the risk of the UASF BIP148 idea. If UASF BIP148 took traction, this would mean that the legacy chain would be wiped out forever, and only BIP148 UASF chain would survive and that would become de-facto BTC.
The good side is that you avoid the possibility of 2 bitcoins forever, the bad side is that if you are on the legacy chain and you sold your 148 coins for BTC you risk lossing it all.
Luckily, BIP148 is now out of the picture. I wouldn't worry about BCC at all.
If you want to worry, worry about november's supposed hardfork to segwit2x... now that 's something I don't see clear at all. I hope the NYA camp gets convinced of the mistake of hardforking in 3 months.
After Aug 1, will BTC and BCC be on the same chain ?
And does the supposed Nov harddork mean the possibility of having 2 bitcoins on entirely different chains or nodes ??