You are using a custom attribute on a stock object like project and auto numbering is enabled for the custom attribute.
In your GEL script, you are doing the following:
Release : 16.1.2, 16.1.3
For example
-- where 123456 is the next sequence number from step 1
select
concat ((string_agg(substr(characters, (random() * length(characters) + 1)::integer, 1), '')), 123456) as auto_generated_attribute
from (values('ABCDEFGHIJKLMNOPQRSTUVWXYZ' )) as symbols(characters)
-- length of word
join generate_series(1, 7) on 1 = 1
-- result TPXYJFP123456
3- Use the result to pass in your xog for the request id.
The request id would be different, but it would never be reused for those created from xog.