I tried doing this and it didn't work.
When I visited the branch yesterday, the woman who served me could see that I was using my other card, and searched for the last transaction on the card that has a hold on it. I was told she would have to call someone to have the hold removed. I was in a rush, so I'll just call them myself, but I'm not optimistic. Surprisingly, she didn't seem to be fussed about me having two cards or how I'd been using them up until early last month, perhaps because I could actually only use one card.
I'll be really irritated if I've just wasted the last 6 weeks, using only one card sparingly (i.e. loss of lots of points), when I could have just cancelled the card, or reported it lost, and had it replaced.
