ציטירנדיקער פּירוש אויף יהושע 9:5

ואם טמאים היו – the unconsecrated produce and the First Tithe into which pure heave-offering fell, for now, he is not able to produce Terumah of the tithe on another place, he separates upon it Terumah of the Tithe and sells them to Kohanim, and the Kohanim can eat them in small bits, in explanation, in a dry condition, like (Joshua 9:12 – not quoted correctly by Bartenura): “[This bread of ours….and see] how dry and crumbly it has become.”

וטלוא, a reference to larger patches, as per Joshua 9,5. We encounter this expression in this sense also in Shabbat 114, i.e. טלאי על גבי טלאי.