[Breza]

Head of data science at a corporation here. People pasting into Excel has been a bane of my job for over a decade.

[quesera]

Yes! I'm sure you know this, but for anyone with similar problems:

You can disable this conversion "feature" in the Excel "Automatic Data Conversions" preference pane.

...and I hope you have better luck getting people in your company to remember this than I have! :)