AWE64 Duplex not working with 2.4.17

I have installed an SB AWE 64, kernel is 2.4.17, audio works fine, but I
cannot play
simultaneous multpile wav or mp3 files, errors reported that something
else has the device open already.

Here's what syslog reports when the modules are loaded:

Dec 29 13:21:13 ws kernel: Soundblaster audio driver Copyright (C) by
Hannu Savolainen 1993-1996 
Dec 29 13:21:14 ws kernel: sb: Creative SB AWE64  PnP detected 
Dec 29 13:21:14 ws kernel: sb: ISAPnP reports 'Creative SB AWE64  PnP'
at i/o 0x220, irq 5, dma 1, 5 
Dec 29 13:21:14 ws kernel: SB 4.16 detected OK (220) 
Dec 29 13:21:14 ws kernel: sb: 1 Soundblaster PnP card(s) found. 

Is there some module option to enable duplex operation?

Please CC: me on replies as I am not on this mailing list, thanks.