multiple ethernet card question

[mc68k]

here's my question:

1 mac
2 network connections to
2 network jacks on a 100BT backbone that won't saturate easily

would this setup see speed increases over:

1 mac
1 network connection to
1 network jack on the same 100BT backbone

basically, does setting up 2 seperate connections to a network on the same machine have any effect on speed? or how does tho OS divide the packet transfers between 2 ethernet interfaces on the same machine?

thanks