Normalizing and Copy out of Reaper

Hello you all,

I have discovered something strange which I cannot understand.
First: when I discovered the SWS/BR Analyze Loudness action, I was very happy because finally I can get my mixes equally loud. Before that I just normalized to 0 dB and I still got puzzled that two mixes that were normalized to 0 dB still were not the same loud. Now I use the LUFS setting -9 LUFS and all my mixes sound equally loud.
Thank you for this fantastic feature!

Now my problem: I mix my own music with an eye on my meter. When I think it sounds okay, I render, and I check my music on a different player and when it's good, only then I normalize my rendered song to -9 LUFS. And then I use CTRL Alt to copy this normalized song to my Mix directory on my HD.
However: when I load that file once again in Reaper to analyze, there is suddenly a difference:
1) the rendered file, loaded back into Reaper and then normalized has -9 LUFS and a peak of 3.7 dBTP
2) the CTRL Alt copy of it and loaded back into Reaper has -9.1 LUFS and a peak of 1.4 dBTP.
Where is this difference coming from?