When using a wrench in a minecart contraption which uses 2 minecarts, right-clicking a minecart with the wrench in order for it to drop doesn't work, whenever a minecart is right-clicked the carts just separate from the contraption placing the blocks in the world (usually being placed in the rail systems and destroying them).

Another bug i found (but i guess it is mostly minecraft's engine fault) is that is almost certain that when a 2-cart contraption is going up a rail track while getting on the max chunk render distance it will bug and in my case it would often go "underground" (bellow the track), making it impossible to retrieve it without damaging the track and the contraption due to the first bug mentioned

This issue has been marked as stale because it has been inactive for 3 weeks. It will be closed if it remains inactive for another 3 weeks.

This issue has been closed since it has been inactive for 3 weeks since it was marked as stale.

The first "bug" is not infact a bug but intentional, whether this will change in a future update is unknown

Is there currently a way of retrieving a 2-cart contraption?

Remove one of the minecarts and then wrench it