I think you're close.

Rather than creating a certificate with the same name in both databases you should backup the certificate from the first database and restore that to the second.

USE DB1

CREATE CERTIFICATE cert1 WITH SUBJECT = 'Certificate for my stuff'

BACKUP CERTIFICATE cert1 TO FILE = 'c:\cert1.dat'

WITH PRIVATE KEY

(

ENCRYPTION BY PASSWORD = 'mypassword',

FILE = 'c:\cert1_privatekey.dat'

)

--

USE DB2

CREATE CERTIFICATE cert1 FROM FILE = 'c:\cert1.dat'

WITH PRIVATE KEY

(

FILE = 'c:\cert1_privatekey.dat',

DECRYPTION BY PASSWORD = 'mypassword'

)