Binding radio buttons

I tried to create radio buttons using the aurelia documentation (https://aurelia.io/docs/binding/radios#booleans). But this solution doesn’t prefill the radio buttons on page load:

<input type="radio" name="myId" model.bind="true" checked.bind="object.MyBooleanVariable" /> Test1
<input type="radio" name="myId" model.bind="false" checked.bind="object.MyBooleanVariable" /> Test2

Adding a snippet ${object.MyBooleanVariable} to my code, it displays e.g. a true on page load, but the respective radio button isn’t preselected.

What I’m doing wrong here?

UPDATE
I found the issue. It was my fault, sorry. Louping through a form I had duplicate input-names.