I reported this 5 months ago that the rule needs to be enforced.

The rule is 1 pricelist per order (which can be broken to be told no that
despite the fact pricelist is many2one with sales order and not m2m, you can
choose to change halfway through which is dubious (although OpenERP kindly
created sale_pricelist_recalculation module for me to fix thank you again).
Otherwise forget the fact that you have 2 currencies, how do you even know
which pricelist you used for which line.  To see why this is dubious go back
to the first line you created and change the qty, remebering you set it in
Euro, look now it is in $.

To follow your logic through not only do you need to change sale order, but
also purchase order and invoice at the very least.

Besides in the real world who honestly places a single order in 2 different
currencies?  The expected result should be to not allow this behaviour IMO

On Sat, May 14, 2011 at 12:12 AM, Harmel Delphine (OpenERP) <
<email address hidden>> wrote:

> Public bug reported:
>
> trunk server revno 3411
>
> having another pricelist in $ (for example)
>
> * Sales/Sales/Sales Orders, Create a sales order using the public pricelist
> (in €)
> * Add a sales order line, for example CPU1 (for a unit price of 75€)
> * change the pricelist on the sales order and select the pricelist in $
> * Add a sales order line, for example CPU1 (for a unit price of 75€
> converted into $ = 96.26$)
> * Click on compute on the sales order line, total = 171,26
>
> Obtained result : there is no difference between product in $ and €,
> moreover the total just make the sum of the two prices !
>
> Expected result : we should see that a price is in € and the other in $
> (add a column on the sales order line) and the total must be the sum of
> all prices in € or all prices in $ not a mix of the two
>
> reported by dha, OpenERP Prof Serv
>
> ** Affects: openobject-addons
>     Importance: Medium
>     Assignee: OpenERP R&D Addons Team 3 (openerp-dev-addons3)
>         Status: Confirmed
>
>
> ** Tags: profserv
>
> ** Changed in: openobject-addons
>     Assignee: (unassigned) => OpenERP R&D Addons Team 3
> (openerp-dev-addons3)
>
> --
> You received this bug notification because you are subscribed to OpenERP
> Addons.
> https://bugs.launchpad.net/bugs/782168
>
> Title:
>  [PS] It is possible to encode product with prices in two different
>  currencies within the same Sales Order
>
> Status in OpenERP Modules (addons):
>  Confirmed
>
> Bug description:
>  trunk server revno 3411
>
>  having another pricelist in $ (for example)
>
>  * Sales/Sales/Sales Orders, Create a sales order using the public
> pricelist (in €)
>  * Add a sales order line, for example CPU1 (for a unit price of 75€)
>  * change the pricelist on the sales order and select the pricelist in $
>  * Add a sales order line, for example CPU1 (for a unit price of 75€
> converted into $ = 96.26$)
>  * Click on compute on the sales order line, total = 171,26
>
>  Obtained result : there is no difference between product in $ and €,
>  moreover the total just make the sum of the two prices !
>
>  Expected result : we should see that a price is in € and the other in
>  $ (add a column on the sales order line) and the total must be the sum
>  of all prices in € or all prices in $ not a mix of the two
>
>  reported by dha, OpenERP Prof Serv
>