As noticed in #31901 comment:28, there is an issue when constructing two charts sharing the same coordinate symbols but not being otherwise related:

sage: M = Manifold(2, 'M', structure='topological')
sage: U = M.open_subset('U')
sage: V = M.open_subset('V')
sage: XU = U.chart('x y')
sage: XV = V.chart('x y')
sage: M.top_charts()
[Chart (U, (x, y))]

The chart XV should also appear as a top chart on M.

CC: @mkoeppe @tscrim @mjungmath @vbraun

Component: manifolds

Keywords: coordinate chart

Author: Eric Gourgoulhon

Branch/Commit: public/manifolds/top_charts_32112 @ 4e316e9

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/32112