How to decide when to abstract common properties?

Imagine we have two types of requests, an InvoiceRequest and a QuoteRequest. How would you prefer the object model (classes) be and the database model ? Which one of the following two make more sense ?

InvoiceRequest: 
 - id
 - amount
 - discount
 - date
 - invoiceSpecificFieldHere

QuoteRequest:
 - id
 - amount
 - discount
 - date
 - quoteSpecificFieldHere. 

Or does this one make more sense?

RequestData:
 - amount
 - discount
 - date

InvoiceRequest: 
 - id
 - requestData: <RequestData>
 - invoiceSpecificProperty

QuoteRequest:
 - id
 - requestData: <RequestData>
 - quoteSpecificProperty. 

I'm not representing a third option using inheritance in purpose.

The question behind this question, is the following; if we go with design 2, we reduce redundancy, however there is something about it that doesn't make me feel comfortable. Which is the fact that reality is not captured correctly. I would argue that discount should be at the same level as quoteSpecificProperty. And putting it inside a box (the requestData object) is a departure from what this represents in the world.