make(1): should := expand twice?

[Joachim Schipper]

Makefile:

A=This is the variable A
FOO=$$A
BAR:=$$A

test:
        echo '${FOO}'
        echo '${BAR}'

I expected, and GNU make gives,

echo '$A'
$A
echo '$A'
$A

However, our make gives

echo '$A'
$A
echo 'This is the variable A'
This is the variable A

Is this sensible, a historical accident that should be preserved, or a
bug? I, at least, was rather surprised...

                Joachim