WBZ (Boston MA) and WBZA (Springfield, MA) They did this for many, many years.
Those were synchronized too i believe. Separate day/night sites aren't unheard of, but not common either. In the case of WQLL, with those nulls in the night pattern they wouldn't be able to cover the target metro from the day site with a similar pattern, and the day pattern would not cover the metro from the night site either, so in a situation like that it makes sense. A lot of these separate site stations seem to come about because they want to run a whopping signal at night but the day site would not allow for a pattern that protect other stations adequately.