Question: If I try to see the suggestion of any word then its only giving me loading ..
can you please tell me whats the issue and how it can be fixed ?

I am not able to find out how to fix it.

Please help me if anyone know how to fix it.[Loading error image](https://i.stack.imgur.com/9oYhN.png)

Answer: 
Perform a FULL OUTER JOIN with `merge`, and remove the suffixes afterward.

```
u = left.merge(right, on=['key1', 'key2'], suffixes=('', '__2'), how='outer') 
u.columns = u.columns.str.replace('__2', '')

u
  key1 key2  valueX  valueY  valueX  valueY
0    A   a1     1.0     4.0     7.0    10.0
1    B   b1     2.0     5.0     NaN     NaN
2    C   c1     3.0     6.0     9.0    12.0
3    B   b2     NaN     NaN     8.0    11.0

```
Not sure why you want duplicate `columns` , but you can using `concat` 

```
Newdf=pd.concat([df1.set_index(['key1',  'key2']),df2.set_index(['key1',  'key2'] )],axis=1).\
        reset_index()
Newdf
Out[711]: 
  key1 key2  valueX  valueY  valueX  valueY
0    A   a1     1.0     4.0     7.0    10.0
1    B   b1     2.0     5.0     NaN     NaN
2    B   b2     NaN     NaN     8.0    11.0
3    C   c1     3.0     6.0     9.0    12.0

```