How to join 2 vector files with common boundary but retain categories ?

[Laxmi Prasad Musunur]

Hi Everyone:

Here's what we are attempting:
  -----		-----		-----------
 |  9  |   +   | 10  |	 =     | 9  |  10  |
 |_____|       |_____|         |____|______|

boundary1       boundary2         boundary12

boundary1    is a vector file with an area with category as 9
boundary2    is a vector file with an area with category as 10

How can they be joined to form vector file boundary12 with the area
category information intact ??

Thank you,
--
Laxmi P. Musunur (LP) School of Forestry, Auburn University, 
AUBURN AL 36849	E-mail:  mlp at forestry.auburn.edu


p.s.

1. Please note that the two areas have a common boundary so v.patch would 
   identify the resulting area with only one category! Hence v.patch can't
   be used.

2. Even in v.digit one can't label the two areas in boundary12 seperately
   because it identifies only one outer area.