mmm, yes, it's possible but not by using the ready-made limit function. Disable that, and the function will be crafted with a little script, something like
on a new download: if IP address is not like 10.* and count of downloads from this ip is more than 1, then disconnect
translated (but not tested) in the actual scripting language is something like (ALT+F6 and put this text)
[download]
{.disconnection reason|only one download at time please|
if={.and|{.match address|10.*|%ip%.}| {.current downloads|ip=%ip%.}.}
.}
it's not very complicated, so it may even work as i imagined