[Dovecot] problem migrating from maildir to dbox

[Ramón Frontera]

Hello,
we want to migrate Mail folders from Maildir to dbox without downtime.
We change the mail_location to dbox in 10-mail.conf and restart dovecot.
After that we use dsync -u user mirror maildir:~/Maildir.
The problem is that if INBOX exists the dsync create a new folder with name like b5893c0a93ff694e551200002dfa3112
Can I migrate to the existing INBOX? or How can I merge the 2 INBOX folders?
Thanks for your help!
Regards,

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Ramon