With dual entry, two connections enter the building at different points, via different routes in the street. If digging damages a cable on one side, the other keeps working.
Two connections running through the same trench do not offer that protection. One digger can then hit both.
Dual entry is a form of redundancy. For the highest IT-Label level, IT1+, redundant fibre is part of the description.
What does this mean for the IT-Label?
Dual entry falls under Connectivity, where redundancy and stability are assessed. It is one of the ways to achieve the redundant fibre mentioned in the description of IT1+ Premium. Two connections through the same trench offer less protection than two separate routes. See also redundancy and SLA.