Is there a possibility to enter for vendor invoice two dates - book entry date and invoice date?

Hello there, Anda. 

If you're referring to adding a Book Entry Date field on your vendor bills, we can customize your form and add this option.

Here's how:

1. Go to the Gear icon, and select Custom fields.
2. Click the Add field.
3. Enter Book Entry Date in the name field, and select Date in the Data type drop-down arrow.
4. Tick Vendor in the  Select category field.
5. Check the box in the Bill from the Select forms.
6. Select Save to confirm.

Please know that custom fields won't appear upon printing the form. However, this option is visible when your vendor receives the email.

On the other hand, if you're referring to adding this field to your customer's forms such as invoices, you just have to repeat the same process and select Invoice in Step 5. 

Check this article to learn more about this process: Add custom fields to sales forms and purchase orders in QuickBooks Online.

Additionally, you can visit this article to learn how to personalize and add specific info to your sales forms: Customize invoices, estimates, and sales receipts in QuickBooks Online.

If you have more questions about customizing forms or any QuickBooks-related concerns. Don't hesitate to reply in the comment section. I'm always here to lend a hand. Stay safe.

Are you trying to do cash or accrual-basis accounting?