You are describing a fork. You have two alternative versions of the last block(s). Eventually only one of them will become part of the canonical history.
To simplify the discussion I consider only the case with a fork of length 1, i.e. when we have two alternative version of the latest block (potentially, the fork(s) can be much longer).
Let's take a simple example (suggested in your comment). Let's say I have two alternative version of a block, whose number is
x (4926211, in your case). Moreover, assume that in version A you have a sequence of transaction
t_1, t_2, t_3) and in block B, you have another sequence of transaction
A becomes part of the canonical history, in block
x you will have only
t_1, t_2, t_3). On the other case, if
B becomes part of the history, block
x will contain only
Basically, you have two possible "universes" in the former scenario the transaction of
T_A will be confirmed and removed from the set of transaction-pool (
t_1, t_2, t_3), while the transaction that belongs to
T_B and not to
T_A will be put in the transaction pool and considered for later insertion. In our example, only