hi @Raulsc , Yes it is possible with out changing at dataset level.
Do one thing create two calculated field with same field and give the calculated field as per your required name for legend then use that calculated field on your visual.
Just see the below example.
If you see these are two field name which is available in my datasets. So the legend name is also the same.
Here I created two new field by using the same field but the calculated field name is different.
Weighted Revenue - Sales
Is Closed - Number of Item
And lastly putting these two new created calculated field in the place of weighted revenue & is closed place.
So these are the some steps you need to follow to renaming your legend.
Thanks & Regards
Biswajit Dash