Try the following in DE8.5:

Create two numeric sting fields on a form. Using the telephone format (999)-999-9999

Now enter some data into the first field. Save the data.

Now right click and copy that data and paste that into the second field using right click paste.

Tab out of second field and data will disappear.

But, if you do the same copy and paste using CTRL + C and CTRL + V works fine.