Denys,
As Shan noted, the concept of Preview Checks, in NAV, is not available. You can preview in BC. Sadly, if you truly want to preview I suggest to my customer running a Test Report to see the Vendor and Check Amounts. If you are using MICR non-preprinted Check Stock, you can always run the checks to PDF and see then on, if it is necessary. And yes, you will need to Void those incorrect or click Reprint Check on the actual real check stock.
Hope this helps.
Thanks,
Steve