When I load and test individually, the first model and second model.
First model:
test loss: 13.146434557001005
Weighted mean absolute percentage error is : 2.941648706059142

Second model:
test loss: 193.99452499602967
Weighted mean absolute percentage error is : 106.5421036013515

When I load and test first and then second model, the loss of first is correct but second is wrong
test loss: 13.146434557001005
Weighted mean absolute percentage error is : 2.941648706059142
test loss: 603501.1757331954
Weighted mean absolute percentage error is : 99.3929476222628

I also confirmed that the weights of individually loaded model are different than when I load the model in succession.