I was hoping to find a baptism for Matthew (and a John) at the same place with same parents...unfortunately I didn't

My guess would be that John and Joel are his brothers. with perhaps John being first born son to parents John and Mary.... but there is not enough evidence to prove or disprove this.
Alternatively, John could be the father.
And sadly the nearest baptism I can see is Matthew Jackson
19 May 1793 BOLSOVER,DERBY,ENGLAND
Parents Richard Jackson and Ann
or
18 May 1808 BOLSOVER,DERBY,ENGLAND
Parents Peter Jackson and Sarah
Bolsover is currently about 15 miles from Belper so it may not be the right one
Milly