We want to run pgrouting 2.x on our test server. Additionally, we want existing applications still run on pgrouting 1.x. Does anyone know, if it's possible installing and running them in parallel?
Currently, we run on Postgres 9.1.9 and PostGIS 2.0.1.
No, I do not think you can do this for the same postgresql version because both versions use a shared library file librouting.so and this file is not compatible between the old and new versions of pgrouting. If you install Postgresql 9.1 and 9.2 for example then you can install pgrouting 1.x on 9.1 and pgrouting 2.x on 9.2 without a problem. In hind sight, maybe I should have done a better job of change the file names to avoid this, but I didn't so its not going to work.
Also I do not think pgrouting 1.x will work with PostGIS 2.0.1 because they removed a lot of functions that pgrouting 1.x uses. It might be possible to solve this problem if you load the PostGIS legacy.sql file.