Problems using ADDCOLUMN when refreshing data

[MrBaseline]

Hi,

I'm using ADDCOLUMNS to create a new table (Project Report) by appending fields to an existing table (cr047_projectmetrics):

Project Report = 
ADDCOLUMNS(
    cr047_projectmetrics, 
    "Project", 'cr047_projectmetrics'[cr047_name],
    "Est. Offtake (# Years)", 
             CALCULATE(MAX('cr047_projectmetrics'[cr047_estimatedofftakenrofyears]),
             FILTER('cr047_well',
             'cr047_well'[cr047_site] = 'cr047_projectmetrics'[cr047_sitelookup]))
)

It actually contains more columns but that's not the issue. 

I have been editing, refreshing, saving and publishing this several times without any issues. Now, suddenly, I get this error for every other table in the model when trying to refrash the dataset:

Failed to save modifications to the server. Error returned: 'The Column with the name of 'Project' already exists in the 'Project Report' Table. '.

I suspect I somehow misunderstand ADDCOLUMNS. If I rename 'Project' to something else, I get the same error for another column name created in the expression above. It's like it runs the expression "on top" of something already defined.

Any help greatley appreciated!

[amitchandak]

@MrBaseline , Addcolumns will add columns to the table cr047_projectmetrics, so it should not match with other column in the table

Try with rename

Project Report =
ADDCOLUMNS(
cr047_projectmetrics,
"Project 1", 'cr047_projectmetrics'[cr047_name],
"Est. Offtake (# Years) 1",
CALCULATE(MAX('cr047_projectmetrics'[cr047_estimatedofftakenrofyears]),
FILTER('cr047_well',
'cr047_well'[cr047_site] = 'cr047_projectmetrics'[cr047_sitelookup]))
)

If this does not help
Can you share sample data and sample output in table format? Or a sample pbix after removing sensitive data.