Bug double cost/price_extra added

[GEM]

Hi,
I installed the module product_variant_multi in v7 with last revision 197.
I creates a product templates.
I add a dimension.
I add an option.
In option line, I enter a value for price_extra and cost_price_extra.
I generate the product variant.
In the variant product, in fields price_extra and cost_price_extra, I have the value entered in fields price_extra and cost_price_extra.
The problem is that the public price calculated do not corresponding to the normal calculation.

Public prices for sale and purchase :

for sale :
list_price * price_margin + price_extra
the result I have :
list_price * (price_margin * 2) + price_extra

for purchase :
standard_price + cost_price_extra
the result I have :
standard_price + (cost_price_extra * 2)

If I comment the line 483, I have not this problem :
#'lst_price' : fields.function(_product_lst_price, method=True, type='float', string='List Price', digits_compute=dp.get_precision('Sale Price')),

contact : <email address hidden>

Thanks for feedback.
Bye