So here we have a parking suspension which is for one day whilst the road is dug up, by the looks of it.
Along pops a traffic warden, the depot isn't far away and this is on a main road, and sticks a PCN on the windscreen at 08:33Then along comes a different traffic warden at 12:40 and dishes out another one.
Note that the second PCN is affixed in a different place to the first one (neither ticket reached the motorist so did the traffic warden put them back in his/her pocket in order to deny the discount - that won't work, it will be 100% once Mr Mustard has finished with them).
Now this being a one day suspension one PCN can legally be upheld. This is the most basic information which traffic wardens, supposedly trained to NVQ level 3 or the equivalent, must know or they shouldn't be let out on the streets to wrongly penalise motorists. In fact, the contract with NSL specifies this.
Mr Mustard is more inclined to think that the information was conveniently forgotten by the traffic warden.
It would be a good use of technology to programme the hand held equipment to prevent the issue of a second PCN for the same contravention at the same place to the same vehicle for the same contravention. This would prevent such wrongful behaviour by traffic wardens.
This sort of double ticketing trick is one reason why the Barnet Council parking department drags the reputation of the council down towards the gutter.