I should add that normally the plea in a debt like this (when there are more than one defendant) says debent & iniuste detinent = they owe and unjustly detain.
In this case the debent has been scrubbed out, leaving only & [sic] iniuste detinent.
Omitting the redundant &, this = they unjustly detain.
This clearly has a significance, but what it is can't be discerned.