I have 2 files, 1.txt and 2.txt which have the following format:

1.txt
:451:1
:451:0
:451:1
and so on..

2.txt
:108:13897187
:108:90890789
:108:76476386
and so on..

I want to combine the files horizontally, I tried paste 1.txt 2.txt as well as cat but both of them are giving me vertical outputs. Please help. Thanks.