Is it possible to run multiple postmasters?

About 2 weeks ago, I reported a problem with 6.5.3 on Linux version
2.2.7-1.23smp (VA-Research).  Basically, we have one gigabyte scale
table that will not index on the text field, although it does index on
a char(1) and a date field.

We been unable to find the cause of the problem ourselves, and the user
community and developers have not yet come up with a solution.

So, as a work-around we contemplated running two postmasters on the
same machine, with different ports and data directories - one would be
6.5.3 which has recent bug fixes that we like alot and a second which
would be 6.5.1 which can successfully create the index that 6.5.3
cannot.

I've been able to get both postmasters running, but the second one to
start seems to interfere with operation of the first.  So my quation
is, can I run two postmasters simultaneously on the same machine?
And if so, how?

Kark DeBisschop