1.mp3--lame->tem.wav--lame->2.mp3 then 1.mp3=2.mp3?

No.

Very descriptive.
If I understand this then No.

1.wav-(lame --preset extreme)->1.mp3-(lame --decode)->2.wav-(lame --preset extreme)->2.mp3 then 1.mp3 == 2.mp3?

Yes

Edit: Ah no. I thought I knew what you were asking but now I'm not sure.

If you are encoding twice from the same source wav with the same settings you will get the same output file.

But the wav file from a decoded mp3 will not be the same as the original because mp3 is lossy. So if that is re-encoded it will not generate the same mp3 again.

Hm? You make 1 mp3, then decode it, and make another mp3 from the decoded file? That would be lossy transcoding, which is... lossy... e.g. not lossless

1.wav-(FLAC -P 4096 -b 1152 -l 0 -q 0 -r 2,2)->1.flac-(flac -d)->2.wav-(wavpack -h)->2.wv-(wvunpack)->3.wav then 1.wav == 3.wav

1.Original-(Photocopier)->1.Photocopy-(Collect from out tray of photocopier)->2.Photocopy-(Photocopier)->2.Photocopy then 1.Photocopy <> 2.Photocopy