Again, I am guessing…
One of these outputs has passed through one Conv1d, the other has passed through two Conv1d’s.
I think the problem is that each Conv1d hasn’t got enough padding, so the input sequence got shortened to 60 timesteps after one Conv1d, and then to 56 timesteps after the two Conv1d’s.
Therefore you can’t add them together because the sequence length doesn’t match up.
I think if you correct the padding used in the Conv1d’s, then the problem will go away.