Memory Alpha says 'Pulaski transferred off the ship sometime prior to Crusher's return', but AFAIK, there is no canon evidence for that.
For all we know, Beverly simply went into 'There can be only one!' berserker mode when she returned and found Pulaski on the ship. They could have used Eye of the Beholder to tell that story, just with a different twist ending:
Beveley: You won't tell the captain or anyone else of the crew, right?
Deanna: I don't think they'd mind. They've never even made a single remark about her unexplained disappearance, after all. But if you don't want me to, of course I won't! What are friends for, after all?
<Both walk away through the corridors, giggling>
For all we know, Beverly simply went into 'There can be only one!' berserker mode when she returned and found Pulaski on the ship. They could have used Eye of the Beholder to tell that story, just with a different twist ending:
Beveley: You won't tell the captain or anyone else of the crew, right?
Deanna: I don't think they'd mind. They've never even made a single remark about her unexplained disappearance, after all. But if you don't want me to, of course I won't! What are friends for, after all?
<Both walk away through the corridors, giggling>