Is it really bad? For the first time in 9 weeks I have a craving for chocolate and I am thinking that another malt toffee bar would be lush! Not if it makes me ill though............the first bar was eaten at 5.30am so 12.5 hours ago..........
I occassionally have 2 in a day if I'm out and about and have had no side effects, but I have a cast iron constitution and don't come out of Ketosis too easily.
The fact your previous bar was 12 hours ago would ppush me in the direction of having another.
TBH another bar has got to be better than falling off the wagon, so maybe just have half, and only have the rest if you feel you really need it