Can you solve this Math Puzzle?

The phone rings and the lady of the house answers, 'Hello.'
'Mrs. Sanders, please.'
'Speaking.'
'Mrs. Sanders, this is Doctor Jones at Saint Agnes Laboratory. When your husband's doctor sent his biopsy to the lab last week, a biopsy from another Mr. Sanders arrived as well. We are now uncertain which one belongs to your husband. Frankly, either way the results are not too good.'
'What do you mean?' Mrs. Sanders asks nervously.
'Well, one of the specimens tested positive for Alzheimer's and the other one tested positive for HIV. We can't tell which is which.'
'That's dreadful! Can you do the test again?' questioned Mrs. Sanders.
'Normally we can, but Medicare will only pay for these expensive tests one time.'
'Well, what am I supposed to do now?'
'The folks at Medicare recommend that you drop your husband off somewhere in the middle of town. If he finds his way home, don't sleep with him.'