If I set serverargs="-bpp 32" in the startx script, and then
try to launch a second version of X using "startx -- :1",
then startx tries to call xinit as "xinit -- -bpp 32 :1"
which is wrong.  Instead it should be "xinit -- :1 -bpp 32".
My solution was to modify the script as described below.

I believe this will pass all command-line arguments after
the default $serverargs, as desired, but extracts the
$display as an optional parameter which must be passed to
xinit before the server options.

49,53c49,54
<           serverargs="$serverargs $1"
<       case "$1" in
<           :[0-9]) display="$1"
<           ;;
<       esac
---
>           case "$1" in
>           :[0-9]) display="$1";;
>               * ) serverargs="$serverargs $1";;
>           esac
65c66
< xinit $clientargs -- $serverargs
---
> xinit $clientargs -- $display $serverargs