In doctrine 1.2 load_data fails with a bogus error when id holders are repeated

Schema fragment:
Invoice:
actAs:
Timestampable: ~
tableName: invoice
columns:
id:
type: integer(4)
primary: true
autoincrement: true
billingDate:
type: date
dueDate:
type: date
hostingAccount_id:
type: integer(4)
relations:
invoiceItems:
class: InvoiceItem
local: id
type: many
foreign: invoice_id
foreignType: one

#
InvoiceItem:
actAs:
Timestampable: ~
tableName: invoiceItem
columns:
id:
type: integer(4)
primary: true
autoincrement: true
name:
type: string(100)
quantity:
type: integer(4)
cost:
type: decimal(10)
scale: 2
notnull: false
default: null
invoice_id:
type: integer(4)

With the following fixture fragment:

Invoice:
testInvoice01:
billingDate: "2009-11-11"
dueDate: "2009-11-16"
owningAccount: TestAcc01
invoiceItems:
invItem01:
name: TestLine01
quantity: 2
cost: 12.99
invItem02:
name: TestLine02
quantity: 1
cost: -2.50

testInvoice02:
billingDate: "2009-11-11"
dueDate: "2009-11-21"
owningAccount: TestAcc01
invoiceItems:
invItem01:
name: TestLine03
quantity: 2
cost: 12.99
invItem02:
name: TestLine04
quantity: 1
cost: -2.50

The reuse of the invItem01 & invItem02 tags - even as children of separate parents causes an error.
The reported error was very confusing:

[Doctrine_Connection_Mysql_Exception]
SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'created_at' cannot be null

Making the child tags unique fixed the issue.
The same fixture loaded without problems in Doctrine 1 (I think 1.0.18 but it's not listed in the released versions above).