Each measure connected to the Value role can be associated with a measure connected to the roles: Comparison Value, Target and Target for Variance. The Value field will only accept more than one measure when no column is linked to the Category field.
The connected measures will be associated according to the order in which they are entered in the respective roles (the first measure in the Value field well will be connected to the first measure connected to the Target and/or Comparison Value and/or Target for Variance fields, and so on).