@bitfreak: There's no limit, that's just not the right syntax

. (So what's happening with what you quoted is that it's just attempting to use the default path twice, which obviously doesn't work. c.f., logread, you'll see the error messages).
Specifically, -d is not a suboption, it only takes a single value, the amount of lines.
The pipe's path can only be customized via an env var.
Code:
FBINK_NAMED_PIPE=/tmp/root/fb_1 fbink -y -14 -d 2
FBINK_NAMED_PIPE=/tmp/root/fb_2 fbink -y -20 -d 5