Ethereal capturing cloned frames from Spanned VLAN TX&RX traffic

When I span both TX&RX VLAN traffic to a Gig monitor port and capture
the traffic using Ethereal, I receive identical cloned frames in my
captured datasets. IE.. two frames contain the exact same contents
including the sequence number.

I am using the SPAN function on a Cisco 6500 running IOS to direct a
single VLAN's traffic to a GigE monitor port. If I SPAN only TX (OR)
RX traffic I do not receive any cloned frames in the Ethereal capture.

I am trying to capture all traffic from all the nodes connected to the
VLAN just as if they were connected to a physical network hub. Anyone
have any idea how I might use the SPAN feature and Ethereal for this
purpose and not get cloned frames?

Thanks Very Much In Advance for Any Help
Regards
Ron

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Cisco Internetwork Operating System Software
IOS (tm) c6sup2_rp Software (c6sup2_rp-JK2S-M), Version 12.1(26)E4,
RELEASE SOFT
WARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by cisco Systems, Inc.
Compiled Sat 15-Oct-05 02:48 by hqluong
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ROM: System Bootstrap, Version 12.1(11r)E1, RELEASE SOFTWARE (fc1)
BOOTLDR: c6sup2_rp Software (c6sup2_rp-JK2S-M), Version 12.1(26)E4,
RELEASE SOFT
WARE (fc1)

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