[ic] Strange behaviour when ordering multiple items w/options

[interchange-users@icdevgroup.org (marc.brevoort)]

Hello group, 

I'm using interchange 4.8.5 and Redhat 7.1 with PostgreSQL. I'm attempting to 
fill the shopping basket with multiple items and options by posting variables 
from the flypage. By looking at a [dump] in page ord/basket.html, I know that 
a correct item+option example looks as follows in the shopping basket:

mv_sku	= '01.01.8001.01.8-I00'
price_group = ''
mv_ip = '0'
code = '01.01.8001.01.8-I00-XL-RED'
mv_ib = 'options'
gift_cert = ''
quantity = '3'

When I attempt to add items via my flypage however, the same dump look as 
follows: (hint: -XS-BLU is appended to the mv_sku)

mv_sku	= '01.01.8001.01.8-I00-XS-BLU'
price_group = ''
mv_ip = '0'
code = '01.01.8001.01.8-I00-XL-RED'
mv_ib = 'options'
gift_cert = ''
quantity = '3'

The relevant cgi variables posted to the basket, as shown by the same [dump],
are: 

          'mv_nextpage' => 'ord/basket',
          'mv_todo' => 'refresh',
          'mv_session_id' => '8thp7RLd',
          'mv_ip' => '0\00\00\00\00\00\00\00\00\00\00\00\00\00\00',
          'mv_sku' => '01.01.8061.01.8-I00',
          'mv_ib' => 'options',
          'submitbutton' => 'Check Out',

This shows that the correct mv_sku is being posted to the form! The variables 
mv_order_item and mv_order_quantity are both posted multiple times (the fact 
that they arrive OK is proven by 'code' and 'quantity' being processed 
correctly by the basket), but for some strange reason the mv_sku that is 
posted as '01.01.8061.01.8-I00' (according to the cgi-variables) arrives in 
the shopping basket with an additional '-XS-BLU' code (which probably has its 
origin in the 'options' table rather than table 'products'). 

Is this behaviour by design or a bug in interchange? What can I do to 
correctly set the mv_sku in the shopping basket? In which file can I find the 
code that actually populates the shopping cart? Getting this part of the 
store to work would be a major breakthrough for me!

Thanks in advance,

grtz
MRJB