Wills From Another State
If a will was made and executed when the testator was domiciled in another state, Pennsylvania will apply that state's laws to determine if the will may be accepted for probate as valid.  For instance, any state may have requirements for subscribing witnesses that are different from Pennsylvania's requirements.

However, Pennsylvania still uses its own laws to interpret the terms of the will, regardless of where the will was made or executed.

See: Will Validity, Generally; Wills, Revoking