I had the same situation several times.
I could jump an opposite piece in two directions but the computer enforced only one.
As if it had something to do with the opposite piece's previous move.
(Example: opposite piece jumped 22-33. I could jump it 38-29 and 39-28. But computer enforced only 39-28)

If both captures are of same length you can choose, the previous move doesn't matter. Can you post one of these games as an example (link to game and position)?

Here's the link, it was the opening.
Whites couldn't capture 38-29.
lidraughts.org/wybTjDvu5yDU

Here the captures aren't of same length, 38x29 takes one, but 39x28x19 takes two. You always have to play the longest capture, so only 39x28 is possible.

All the rules of the game can be found here:
lidraughts.org/variant/standard