To be fair to MPs they are not expected to be lawyers in order to make laws.
They, that is MPs, are expected to be given sound and robust advice by <cough, cough, wheeze> uk civil servants.
But an even bigger principle still is that it is acceptable to make a mistake - everyone can and usually everyone does.
And so, the matter becomes:
+ what needs to be done to put things right as in the intention of the law/act in the first place (does the wording of law/act conflict with the intention of same law/act?)
+ how to process the changes (if any) required? Another vote at the House?
+ how did the mistake or oversight arise (we operated on draft 22 of the law/act not realising it had been updated twice to draft 24?)
+ what can be done to ensure similar circumstances are not repeated?
And I'd add to those:
+ how much has the rework cost?
Reasoning: civil servants, quangos, advisors and consultants don't really mind getting paid twice or more for doing the same bit of work.
Reasoning again: MPs are a bit like the owner of a large luxury ship. They might say: take us to the Canaries! It then becomes the responsibilities of support staff to make "Take us to the Canaries" doable and practicable yes?