how to remove certain columns from dataframe

I am just starting with python and pandas. I have a dataframe that looks like this:

1  2.3  1  2.5  1  4.52  2.3  2  2.5  2  4.53  2.3  3  2.5  3  4.54  2.3  4  2.5  4  4.55  2.3  5  2.5  5  4.5

I am trying to remove all the identical columns except for the first one so I want to be left with:

1  2.3  1  2.5  1  4.52  2.3  2  2.5  2  4.53  2.3  3  2.5  3  4.54  2.3  4  2.5  4  4.55  2.3  5  2.5  5  4.5

I have managed to obtain the indices of the identical columns in a list duplicate_cols.`duplicate_cols=[2,4] in the example above.

But when I try to extract them from the dataframe with:

dataframe.drop(dataframe.columns[duplicate_cols], axis=1)

All the columns are removed (the ones with 1 2 3 4 5 I mean). I was expecting the first column to stay.

Can anyone tell me where I am doing something wrong?