No, these operations are not doing the same, as adding tensors via:
combined = pool4_scored + pool5_upscored

will perform the addition in each element while torch.cat will concatenate both tensors into a new (larger) tensor:
a = torch.ones(3)
b = torch.ones(3) * 2

combined = a + b
print(combined)
> tensor([3., 3., 3.])

combined = torch.cat((a, b))
print(combined)
> tensor([1., 1., 1., 2., 2., 2.])