As we teach half of the classes, we get half the credit. So in your example 1.5.
That was the rule at my old school. Thus if you did a team course, you could only do it as an overload, and would be paid (when I started) $900.
And yet the administration was constantly asking us to develop team courses, apparently because the board thought they were innovative. The brought in people to lecture us on best practices in team-taught classes and twisted our arms to make us come. The deans brought it up in conversation. The president would mention it in his yearly hectoring of the faculty.
I used to work in industry, which had its downsides, but the lack of understanding on the part of higher ed leadership between goals and funding boggles my mind. What makes it even stranger is that many of these admins had stints as social science faculty, so the place of human motivation and agency should be a natural way for them to think about these things. But its as though they had some sort of ECT that wiped out that knowledge, to be replaced by a sort of magical thinking.
End of the rant and back to the question.
I had one admin who was supportive of team teaching, encouraged it, and both faculty got load credit. Another only gave load credit if the course enrollment exceeded a certain threshold, which was not normally the case. A third case, different school, comes to mind, and faculty could team teach some specially approved courses, of where there were just a handful. But there was a system in place to allow that, based on the course design, and the value that team teaching would bring to the course. (Which seems like a good system.)