The "staff" in Matt 10:10 must be understood by what has been said in relation to the "spares" of other travelling provisions - it was not to be an extra staff. Thus, the travelling evangelists were allowed one staff but not two. This then agree with Mark 6:8 for just one staff (not two).
Ellicott agrees in his comment in Matt 10:10
Neither shoes, nor yet staves.--The apparent contradiction between
these words and St. Mark's "nothing except a staff only," "be shod
with sandals," is explained by what has been said above. They were to
have none of the reserved comforts of common travellers, no second
staff in case the first should break, no second pair of shoes in which
to rest the worn and weary feet.