This is not a reproducible example, as we don't have access to your data. Please You share those either with dput, or datapasta, or Github Gist, or something else. However, if you fighure out the problem by yourself or from my attempted explanation below, you don't need to share it, but keep this in mind for future posts.
What I understand from the comments in your code is that you want to select 2 rows randomly from both the datasets. Is that correct? I'm not sure as you used 3 and then did something that doesn't seem right.
If so, you can't use sample this way. If DF is a data.frame with C columns and R rows and you use sample(DF, k), it doesn't choose k rows among total R rows randomly, rather it chooses k out of C columns randomly.
The correct approach will be to create a sequence from 1 to the number of rows of the dataset you have, and choose 2 numbers from that sequence. Then, select the corresponding rows of the dataset. I'm not sharing the code, as it'll be fairly straightforward.
If you prefer to use dplyr, there is a function sample_n, which you can explore also.
Hope this helps.