dividing IV antibiotics doses between 2 lumens

We have a hemodialysis patient whose source of infections is (presumably) her double-lumen central line. Apparently the line can't be replaced (for now). The nephrologists have been dividing the total antibiotic doses so that 1/2 the dose is given into each lumen. Has anyone else seen this or any evidence that this is any better than giving the entire dose through one lumen?

Thanks

Jane