can we store two text box values in single column of a table ?

Well, you can concatenate the strings in the text boxes into a single sitrng and delimit with a proper delimiter like ; This would be something like:

string concatenated = string.Format("{0};{1}", textBox1.Text, textBox2.Text);

After that you can insert the data into the column in the database.

However, if those two text boxes represent different data, I wouldn't advice to use concatenation, but to add more columns into the table to hold all the independent data. Few reasons for this:
- searching is easier and more reliable
- changes in the data are easier and more reliable to handle
- possible indexing works better etc.