I don't think they ever let people trade 1 TS for 2 CS, but they have let people trade 1 TS for 1 CS plus an extra couple of snacls. I think they also gave a choice once for 1 CS, plus a lanyard and pins.
I think the reason they did that was because so many people did not realize that they have to make ADRs in advance. However, Disney has really tried to make people aware of the need for ADRs in the past year, so they may not allow the trades this year. Then again, it may depend on how full the restaurants get during
free dining this year.
We were able to trade 2 TS for 2 CS on our trip a few weeks ago. We just ran out of time to use up those last TS credits.