repeating chords with just the duration

[Knute Snortum]

I don't use chordmode much, but this snippet doesn't do what I thought it
would:

\version "2.25.13"

{
  \new ChordNames \chordmode { a1:7 4 }
}

It produces an "A7sus4 3" instead of two A7's.  Is this a bug, or is that
syntax just not supported?

--
Knute Snortum