BUG #8247: Duplicate database names - pg_dump backup fails

The following bug has been logged on the website:

Bug reference: 8247
Logged by: Paul Macdonald
Email address: paul(dot)macdonald(at)ssc-spc(dot)gc(dot)ca
PostgreSQL version: Unsupported/Unknown
Operating system: Debian Sarge
Description:

Postgres version: 7.4.7-6sarge1

Issue: pg_dump fails due to unexpected duplication of database name
("avipads"). Dropdb will remove one instance of the database name, but
unable to remove the second instance.

Scope: This specific database is used on multiple servers nationally. Three
of our servers have this issue, the majority do not. The issue only affects
our ability to locally backup the "avipads" database. The servers having the
problem are clustered pair systems. The other cluster pair servers do not
have the problem.

Name | Owner | Encoding
-----------+-------------+-----------
avipads | | SQL_ASCII
avipads | avimgr | SQL_ASCII
rtadb | rtafbackend | SQL_ASCII
rtafdb | rtafbackend | SQL_ASCII
template0 | postgres | SQL_ASCII
template1 | postgres | SQL_ASCII

When a new version of the database is available for installation, the
installation script does the following steps
a) remove the old database
su - avimgr -c "dropdb --quiet --username=avimgr avipads" || true
b) remove the avimgr user
su - postgres -c "dropuser --quiet avimgr" || true
c) create the avimgr Posgresql user
su - postgres -c "createuser avimgr --no-adduser --createdb --quiet; true"
2> /dev/null
d) install the new database
su - avimgr -c "/apps/avipads/voicedb/restorevoice
/apps/avipads/voicedb/vdb2.5.1.pg"

I would like details on how to successfully remove both "avipads" databases,
in order to have the pg_dump be functional again.