why an advanced LSTM model produce the same results as a simpler one?
If you can achieve high results with a simpler model, it is great news! Always choose simpler models because they may be wrong on fewer things than complex ones (Occam's Razor).

Nothing to be worried about, this can happen.

Obviously, it is always possible that there is an implementation problem, so always make sure your code works better.

Reproducing results from papers is always difficult since many things can differ between your work and theirs:


Code might be different
Data might be different
Package versions may be different
Randomness might be controlled differently
Weights may be initialized differently
Data might be fed into the model differently
Hardware may be different which, especially with GPU can cause slight difference in results