Stay alert! Nowadays, many places, including ours, invite multiple
candidates for second visits (for a single position).
The department is afraid that the No1 candidate may not come, as s/he may
have multiple offers. Usually, it takes a quite long time for the No1
candidate to make a decision. So the department invites multiple candidates
for a second visit. Even if the No1 candidate does not come, it can quickly
send the offer to the next candidate. This is something completely beyond
your control unless you have offers from similar places.
Don't take everything for granted until you see a WRITTEN offer letter. Just
keep showing interest.
In terms of bringing a spouse: if your spouse has limited vacation time (e.g
. works in a company), I would recommend not bring in your spouse for a
second visit unless they send you a written offer letter first. If the
department does not invite your spouse, there is no need to bring him/her.
If the department invites your spouse but haven't sent you an offer letter
yet, just tell the department, I am happy to let you know more about me and
I am also interested in knowing more about you. For this visit, we will
mainly explore whether there is a professional fit between us. I will bring
in my family for the visit when it is my turn to make a decision.
Best of luck!!