diff --git a/issue10363.diff b/issue10363.diff
new file mode 100644
index 0000000..21c1231
--- /dev/null
+++ b/issue10363.diff
@@ -0,0 +1,96 @@
+diff --git a/trytond/trytond/modules/production/bom.py b/trytond/trytond/modules/production/bom.py
+index dc3faeb..3f9c369 100644
+--- a/trytond/trytond/modules/production/bom.py
++++ b/trytond/trytond/modules/production/bom.py
+@@ -1,6 +1,6 @@
+ # This file is part of Tryton.  The COPYRIGHT file at the top level of
+ # this repository contains the full copyright notices and license terms.
+-from trytond.model import ModelView, ModelSQL, DeactivableMixin, fields, Unique
++from trytond.model import ModelView, ModelSQL, DeactivableMixin, fields
+ from trytond.wizard import Wizard, StateView, Button
+ from trytond.pyson import Eval
+ from trytond.pool import Pool
+@@ -21,13 +21,15 @@ class BOM(DeactivableMixin, ModelSQL, ModelView):
+         Compute factor for an output product
+         '''
+         Uom = Pool().get('product.uom')
++        output_quantity = 0
+         for output in self.outputs:
+             if output.product == product:
+-                if not output.quantity:
+-                    return 0.0
+-                quantity = Uom.compute_qty(uom, quantity,
+-                    output.uom, round=False)
+-                return quantity / output.quantity
++                output_quantity += Uom.compute_qty(
++                    output.uom, output.quantity, uom, round=False)
++        if output_quantity:
++            return quantity / output_quantity
++        else:
++            return 0
+
+     @classmethod
+     def copy(cls, records, default=None):
+@@ -67,11 +69,14 @@ class BOMInput(ModelSQL, ModelView):
+         super(BOMInput, cls).__setup__()
+         cls.product.domain = [('type', 'in', cls.get_product_types())]
+         cls.__access__.add('bom')
+-        t = cls.__table__()
+-        cls._sql_constraints = [
+-            ('product_bom_uniq', Unique(t, t.product, t.bom),
+-                'production.msg_product_bom_unique'),
+-            ]
++
++    @classmethod
++    def __register__(cls, module):
++        super().__register__(module)
++        table_h = cls.__table_handler__(module)
++
++        # Migration from 6.0: remove unique constraint
++        table_h.drop_constraint('product_bom_uniq')
+
+     @classmethod
+     def get_product_types(cls):
+diff --git a/trytond/trytond/modules/production/locale/ca.po b/trytond/trytond/modules/production/locale/ca.po
+index 1b5da12..b45e93c 100644
+--- a/trytond/trytond/modules/production/locale/ca.po
++++ b/trytond/trytond/modules/production/locale/ca.po
+@@ -376,10 +376,6 @@ msgctxt ""
+ msgid "Waiting"
+ msgstr "En espera"
+
+-msgctxt "model:ir.message,text:msg_product_bom_unique"
+-msgid "Products can only appear once on each BOM."
+-msgstr "Un producte només pot aparèixer una vegada a cada LdM."
+-
+ msgctxt "model:ir.message,text:msg_recursive_bom"
+ msgid "You cannot create a recursive BOM for product \"%(product)s\"."
+ msgstr "No podeu crear una LdM recursiva pel producte \"%(product)s\"."
+diff --git a/trytond/trytond/modules/production/locale/es.po b/trytond/trytond/modules/production/locale/es.po
+index 7cbd0a9..923fa40 100644
+--- a/trytond/trytond/modules/production/locale/es.po
++++ b/trytond/trytond/modules/production/locale/es.po
+@@ -376,10 +376,6 @@ msgctxt ""
+ msgid "Waiting"
+ msgstr "En espera"
+
+-msgctxt "model:ir.message,text:msg_product_bom_unique"
+-msgid "Products can only appear once on each BOM."
+-msgstr "Los productos solo pueden aparecer una vez en cada LdM."
+-
+ msgctxt "model:ir.message,text:msg_recursive_bom"
+ msgid "You cannot create a recursive BOM for product \"%(product)s\"."
+ msgstr "No puede crear una LdM recursiva para el producto \"%(product)s\"."
+diff --git a/trytond/trytond/modules/production/message.xml b/trytond/trytond/modules/production/message.xml
+index f97efb1..b12c6e4 100644
+--- a/trytond/trytond/modules/production/message.xml
++++ b/trytond/trytond/modules/production/message.xml
+@@ -6,8 +6,5 @@ this repository contains the full copyright notices and license terms. -->
+         <record model="ir.message" id="msg_recursive_bom">
+             <field name="text">You cannot create a recursive BOM for product "%(product)s".</field>
+         </record>
+-        <record model="ir.message" id="msg_product_bom_unique">
+-            <field name="text">Products can only appear once on each BOM.</field>
+-        </record>
+     </data>
+ </tryton>
diff --git a/series b/series
index 7f04424..e30e484 100644
--- a/series
+++ b/series
@@ -53,3 +53,5 @@ issue11051.diff # [account_invoice_defer] Add default company to invoice deferre
 issue11049.diff # [account_invoice_defer] Raise user error message for account not configured (only 6.0)
 
 issue11240.diff # [account_invoice] Can't reconcile by wizard in multicompany - patch pendent de core
+
+issue10363.diff # [production] Remove unique product constraint on BOM