Either way works fine and is understood by the player. The chord name A- could also be written four times.
I used the double bar repeat as I only needed to make just the single entry (2 birds...)
As well as to show it in use.

The double bar repeat is most useful when you have a two-bar phrase that is repeated in the subsequent two bars.
Sure, you could put it in repeat brackets, but then the chart wouldn't be "square".

It's just another tool in your kit.
)BOB