Name on voucher - passport name

We have ordered 4 Japan Rail Passes through an agency and just received the vouchers.

On one of the vouchers, the name doesn't match the name on the passport exactly:

Name on passport:

Surname: Bak
Given name: Niels Johannes Frydshou

Name on Voucher

Bak Niels J Frydshou

So the name "Johannes" has been shortened to "J". We are a bit worried that the voucher will not be accepted, because the full name is not indicated, only a shortening.

Should we try to get a new voucher? - we leave on 20 September (less than 1 month)