This is an example from Manchester, which I also doubt was authorised… https://goo.gl/maps/4aQHgjBJkWq
At least in this example the confusion risk has been eliminated by extending the arrow length to separate the destinations.
It also does appear on trunk road signs! There is a set here (https://goo.gl/maps/aooT1xSRWqq) on the A627(M), which were erected well after LTN 1/94 came out. Whether or not the then HA authorised it is unknown of course.
I suspect the intention behind them is to demonstrate a lane does actually go both ways without spending extra money on a Dia. 877, or in the case of the A627(M) example, a gantry.
We have far too many situations where selecting a lane in good time is made difficult due to misleading or incorrect signs, and without a thorough design guide for ‘unusual’ scenarios this problem isn’t likely to go away any time soon.