At the time of your appointment you may handover the notarised copy of your
Testimonials to the concerned person of the company and if required show the originals.
You can ask the concerned person finalising your joining to take out a photocopy from the originals in the office and varify it with the originals and confirm that the originals are seen and varifed.
If the company states that they need to keep the originals for varification, ask them to use the notarised copies/seen and varified copies.
You can mention in your joining report that you have joined duties after completion of formalities e.g........ and that your original docs e.g.... are seen and varified by the concerned person name... and following documents ..............are received by concerned person name...
Your original docs are your property.
As a matter of fair practice you can ask all establishments e.g a bank to supply you copies/certified copies of all docs submitted/signed by you.