Its standard TM behaviour when resolving items that if it encounters a localised item still at v1 (so unchanged from the parent) it uses the parent item when sending to translation management systems.
This happens silently behind the scenes and is not opaque to users, it would be better if this "decision" to resolve to parent was indicated to users some how - either through notification framework or shown in the translation job itself.
Clients can find themselves in a situation where they need to update global content in a parent item, but not want that change to be blueprinted to children. In this case they'll localise child items (that stay at v1) and then change the parent (which becomes v2).
In this situation, when sending a job for translation they are unaware that its the parent content being sent - which might now be different to whats actually in the child when it was first localised.
The TM behaviour expects the editor to change the parent first, then localise the child, then remove the change from the child (and therefore generate a v2).