Length of merged audios

Hi
I am new to Audacity. My question is about merging multiple audio files into one longer file.
I have been using a different program to do this, which has worked well but is cloud based and I wanted to keep in local to my computer.

But when I merge the audio files, using the two different formats. Audacity comes out nearly twice as long in length as the other program I use. And it seems really odd. Why is that please, does anyone know?

The other program lines up with the length I know the recording should be.

Does audacity compress them differently somehow.

Thanks in advance for any opinion.