Project payback costs

 Hi, I work for a project mfg company. When we do a project payback for a project borrow transaction, sometimes, when there is a cost variance, we get a dr and a cr to the borrowing project resulting in the borrowing project to never have the $ taken off.

EX. B project borrows and gets 150K dr

       L project gets  150k cr

When paided back with a cost variance less of what was borrowed of 1k

     B project gets a 150K cr, 1k cr and a 150K dr result 149k still on the project

     L project gets a 150k dr

What's up and what is the net effect on the GL?