The problem is, that Thunderbird uses more fields for an contact than Pegasus does (e.g. Pegasus has one 'name' field, Thunderbird two).
I don't know, if a converter exists, maybe you have to changethe tab-file manually.
Remove the tab between the contact names and put the e-mail address right after the name in the tab-file. Now the name and e-mail address
will be displayed correct in Pegasus.
Note: Please don't write your whole message in capital letters.
kind regards