When you import the contacts from Senta to the new Contact Hub it appears to be duplicating the contacts.
For example, the director is a contact on the Limited company in Senta so it pulls through the company and the individual both as organisations.
The director also, has their own individual record for their self assessment in Senta so the import then pulls them through again as an Individual in the Contact Hub.
There is no way currently to merge these contacts.
I also don't know if the organisation and individual records for the person are merged if this would allow the search on the proposal screen for a contact to pull through Company details + Primary contact details or not.
To add to the fun the contact hub has also assigned one proposal to the Person's organisation record and all the other proposals to the Person's Individual record - there seems to be no reason for this as the work relates to a self assessment and used the Person's individual record in Senta and not the Company record in Senta.
The only way to correct this is seem sot be to go into every record and manually merge them