any debugging on with this?
can you try d_http?

I'm not sure how this is coming up referencing a line in Web::HTTP

that was with no debugging.  here's what i get with --d_http:

2005-11-02 13:43:03.8301 Found Template::Stash::XS!
2005-11-02 13:43:03.8345 Server ./slimserver.pl accepting http connections on
port 9000
2005-11-02 13:43:04.3028 Adding handler for regular expression
/plugins/Favorites/favorites_list.htm
2005-11-02 13:43:04.3065 Adding template directory
/Users/kpearsall/BRANCH_6_2_x/Plugins/Favorites/HTML
2005-11-02 13:43:04.3268 Adding handler for regular expression
/plugins/RadioIO/index.htm
2005-11-02 13:43:04.3288 Adding template directory
/Users/kpearsall/BRANCH_6_2_x/Plugins/RadioIO/HTML
2005-11-02 13:43:04.3937 Adding handler for regular expression
/plugins/ShoutcastBrowser/index.htm
2005-11-02 13:43:04.3961 Adding template directory
/Users/kpearsall/BRANCH_6_2_x/Plugins/ShoutcastBrowser/HTML
2005-11-02 13:43:04.5552 Adding handler for regular expression
/plugins/Live365/loginout.(?:htm|xml)
2005-11-02 13:43:04.5610 Adding handler for regular expression
/plugins/Live365/index.(?:htm|xml)
2005-11-02 13:43:04.5626 Adding handler for regular expression
/plugins/Live365/search.(?:htm|xml)
2005-11-02 13:43:04.5641 Adding handler for regular expression
/plugins/Live365/action.(?:htm|xml)
2005-11-02 13:43:04.5655 Adding handler for regular expression
/plugins/Live365/browse.(?:htm|xml)
2005-11-02 13:43:04.5696 Adding template directory
/Users/kpearsall/BRANCH_6_2_x/Plugins/Live365/HTML
2005-11-02 13:43:04.6790 Adding handler for regular expression
/plugins/Health/index.(?:htm|xml)
2005-11-02 13:43:04.6813 Adding template directory
/Users/kpearsall/BRANCH_6_2_x/Plugins/Health/HTML
2005-11-02 13:43:04.7460 Adding handler for regular expression
/plugins/Podcast/myPodcasts
2005-11-02 13:43:04.7481 Adding handler for regular expression
/plugins/Podcast/myPodcasts2
2005-11-02 13:43:04.7524 '`plugins/Podcast/myPodcasts2' is not the same as
'`plugins/Podcast/myPodcasts' at /Users/kpearsall/BRANCH_6_2_x/Slim/Web/HTTP.pm
line 1996
2005-11-02 13:43:04.7541 Adding template directory
/Users/kpearsall/BRANCH_6_2_x/Plugins/Podcast/HTML
2005-11-02 13:43:04.7776 Adding handler for regular expression
/plugins/Picks/index.htm
2005-11-02 13:43:04.7800 Adding template directory
/Users/kpearsall/BRANCH_6_2_x/Plugins/Picks/HTML
2005-11-02 13:43:04.8674 Adding handler for regular expression /plugins/RPC/rpc.js
2005-11-02 13:43:04.8702 Adding handler for regular expression /plugins/RPC/rpc.xml
2005-11-02 13:43:04.8893 Adding handler for regular expression
/plugins/RandomPlay/randomplay_settings.(?:htm|xml)
2005-11-02 13:43:04.8931 Adding handler for regular expression
/plugins/RandomPlay/randomplay_mix.(?:htm|xml)
2005-11-02 13:43:04.8948 Adding handler for regular expression
/plugins/RandomPlay/randomplay_list.(?:htm|xml)
2005-11-02 13:43:04.8969 Adding template directory
/Users/kpearsall/BRANCH_6_2_x/Plugins/RandomPlay/HTML
2005-11-02 13:43:04.9795 Accepted connection 1 from 127.0.0.1
2005-11-02 13:43:04.9902 reading request...
2005-11-02 13:43:04.9924 HTTP request: from 127.0.0.1
(HTTP::Daemon::ClientConn=GLOB(0x407bfa4)) for GET HTTP/1.1
/browsedb.html?hierarchy=age,track&level=0 
2005-11-02 13:43:04.9958 HTTP parameter hierarchy = age,track
2005-11-02 13:43:04.9971 HTTP parameter level = 0
2005-11-02 13:43:04.9990 processURL Clients: 
2005-11-02 13:43:05.0009 Generating response for (htm, text/html) browsedb.html
2005-11-02 13:43:05.0022 generating from include.html
2005-11-02 13:43:05.1043 generating from browsedb_pwdlist.html
2005-11-02 13:43:05.1222 generating from browsedb_list.html
2005-11-02 13:43:05.2279 generating from browsedb_list.html
2005-11-02 13:43:05.2390 generating from browsedb_list.html
2005-11-02 13:43:05.2497 generating from browsedb_list.html
2005-11-02 13:43:05.2623 generating from browsedb.html
2005-11-02 13:43:05.3015 End request: keepAlive: [] - waiting for next request
on connection = close

2005-11-02 13:43:05.3038 More to send to 127.0.0.1
2005-11-02 13:43:05.3061 No more messages to send to 127.0.0.1
2005-11-02 13:43:05.3073 End request, connection closing for:
HTTP::Daemon::ClientConn=GLOB(0x407bfa4)

I can't reproduce this, so I'm guessing a bit here.  

try changing HTTP.pm line 1995 to:
$::d_http && msgf("Adding handler for regular expression %s\n",$regexp);

might fix things if what i think it happening is correct.  something in the
regex in this case is breaking msg() so you end up with that extra msg() that
doesn't seem to appear anywhere in the code.

Not sure what's happening here, but it's not going to be fixed for 6.2.1

stopgap fix committed to trunk at change 5055.  The web pages for podcast plugin
are not functional, so disabling the handlers should remove te warning and have
no visible effect for the user.

leaving open in case a more permanent solution comes along.

This seems reasonable to me.