Yes. All 48 seeds end up in a store, so the stores can finish 24 to 24. Any other split has a winner, and nothing else breaks a tie.
Yes. There are 48 seeds in play, and once the game ends every one of them is in a store. If each store holds 24, the game is drawn and neither player wins.
How common is it?
A draw is not rare between careful players, because both sides are always counting the same seeds. There is no tie-break and no extra round. If you want a result, plan the last few sowings with the ending rule in mind, since the seeds left on a side go to its owner.
The strategy guide shows how to squeeze out the single seed that decides a close game.