How to make vbs loginscript check that mapped drive exists

Hello experts :)

I am facing a problem, makeing the correct vbs commands in my script.

I want to make the login script, which only purpose is to map some shared folders as drives.
I have made the script below already, but my problem is, that if ex. drive P: exists, an error turns up saying that it is already in use. I would like to know how I can make it just pass by, if the drive letter already is in use ?

Script:
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Option Explicit
Dim DriveLetter1, DriveLetter2, RemotePath1, RemotePath2
Dim objNetwork
Set objNetwork = CreateObject("WScript.Network")

DriveLetter1 = "X:"
DriveLetter2 = "P:"

RemotePath1 = "\\server1\scan"
RemotePath2 = "\\server2\company"

objNetwork.MapNetworkDrive DriveLetter1, RemotePath1
objNetwork.MapNetworkDrive DriveLetter2, RemotePath2


Wscript.Quit
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Thank you in advance :)