After combining two dataframes, I have this dataframe:

```
ip                 accountname      name      gsm
192.168.1.1        aaaa             john doe  850
192.168.1.2        bbbb             jane doe  860

```

I want to convert dataframe to json:

```
json_df = df3.set_index('ip').T.to_json()

```

And I have : 

```
ValueError: DataFrame columns must be unique for orient='columns'.

```

IPs are unique in dataframe. Index column is unique. How can I avoid this error? any advice would be appreciated.