double edges appearing in graph

Consider the following graph:

digraph "server"
{
graph["splines"="curved","overlap"="scalexy","rankdir"="LR"]
node["fontsize"="8px","fontname"="arial","shape"="rect","margin"=0,"pad"=0,"style"="solid"]
"1" -> "2" ;
}

GraphViz renders this with two edgest between rectangle 1 and rectangle 2. I would have expected only 1. Is this normal?

What version of Graphviz are

What version of Graphviz are you using? There was a bug like this a while ago, but it has been fixed.

Not sure

I'm actually not sure. It's probably a few years old, but the dot.exe doesn't have version information and I'm not actually sure where to look. Perhaps I will just try upgrading.

If you run dot.exe -V, this

If you run dot.exe -V, this will give you the version information. I am almost certain an upgrade will fix the problem.

Double edges: even with latest version

I just tested: the problem is in the current version (2;38) and disappear if splines=curved is removed from directives...

This is a bug that has been

This is a bug that has been fixed a while ago. Your best bet is to get version 2.40 if possible.