I hear this sentence when I work with teams led by two people at the top. Rarely said openly. Usually in passing.

It isn't a sign of disloyalty but of missing clarity. When it isn't defined who decides what, people pick whoever they expect the better answer from.
For the two leaders this feels harmless for a long time. They notice it only when decisions are made twice – or not at all.

Good co-leadership doesn't need harmony. It needs clarity about where one person decides alone – and where they don't.

That clarification takes half a day. Not having it costs years.