On Saturday against Chesterfield a well-placed Ian Ross free kick saw them snatch victory in the final minute.
It was the second time in two pre-season games that Trinity had come back from behind to claim a win as in the previous match against Worksop they ran out 3-2 winners after going 2-0 down.
Against Chesterfield they fought back from Jack Lester's early opener to win thanks to second-half goals from new boy Gareth Davies and trialist Ross.
Chesterfield had opened the scoring after six minutes, but in the second half Trinity pressure was rewarded when ex-Spirerite Davies scored with a long-range effort which took a deflection and found its way into the net and then Ross's late, late show sealed the win.
But on Tuesday night the Blues went down to a disappointing 2-0 defeat to Grimsby Town.
They started well enough, Liam Needham forcing Mariners' goalkeeper Phil Barnes into a good save, but seconds later they conceded a goal when a screamer from Till gave Adam Sollitt no chance.
Grimsby doubled their lead after half an hour when Butler managed to squeeze the ball past Sollitt.
A poor game drifted towards the final whistle with Trinity having some good spells of possession without finding the net.
The feeling in the Trinity camp was that the Blues gifted Grimsby their goals which might have come from lack of fitness which the club will be working on in their next training sessions.