Filling the gaps in values of IDENTITY column

Question

I have a table with an IDENTITY column

[Id] int IDENTITY(1, 1) NOT NULL

After some rows beeing added/removed I end with gaps in Id values:<

Answer 1

I cannot control the part which requires ID columns to be in sequence.

This sounds like there is program logic which assumes there are no gaps--correct?

I need this to keep two different databases in sync.

It's still not clear what you mean. If the actual values in the IDENTITY column are not meaningful (not used as foreign keys by other tables), you can just do this:

DELETE FROM db1.table
SELECT col1, col2, col3 /* leave out the IDENTITY column */ 
INTO db1.table FROM db2.table