Moving every other row to a new column and group pandas python

I have an example data set that's much smaller than my actual data set, it is actually a text file and I want to read it in as a pandas table and do something with it:

import pandas as pd
d = {
     'one': ['title1', 'R2G', 'title2', 'K5G', 'title2','R14G', 'title2','R2T','title3', 'K10C', 'title4', 'W7C', 'title4', 'R2G', 'title5', 'K8C']
    }
df = pd.DataFrame(d)

Example dataset looks like this:

df

Out[20]:  
      one
0   title1
1      R2G
2   title2
3      K5G
4   title2
5     R14G
6   title2
7      R2T
8   title3
9     K10C
10  title4
11     W7C
12  title4
13     R2G
14  title5
15     K8C

I added a second column called 'value':

df.insert(1,'value','')
df

Out[22]: 
      one      value
0   title1
1      R2G
2   title2
3      K5G
4   title2
5     R14G
6   title2
7      R2T
8   title3
9     K10C
10  title4
11     W7C
12  title4
13     R2G
14  title5
15     K8C

I want to first move every other row over to the 'value' column:

      one    value
0   title1    R2G          
1   title2    K5G  
2   title2    R14G 
3   title2    R2T    
4   title3    K10C          
5   title4    W7C            
6   title4    R2G           
7   title5    K8C  

I then want to group by the title name, since there might be more than 1 values for the same title:

     one     value
0   title1    R2G          
1   title2    K5G, R14G, R2T   
2   title3    K10C          
3   title4    W7C , R2G                        
4   title5    K8C  

How can this be achieved?