It seems that tere is a second ISBN Number for e-books
Or do you think that there should be added two records in the database - one for print and one for e-book?
> It seems that tere is a second ISBN Number for e-books
Yes, that's correct.
> Or do you think that there should be added two records in the
> database - one for print and one for e-book?
This would be one way of handling it. For records that also have an actual print record, I'd simply enter the record's print info (including the print ISBN) and ignore the e-ISBN (or put it into 'notes').
Is there any practical use case for storing the e-ISBN in a dedicated field?
I don't know, maybe it is the same answer as 1996 if anybody would ask for the practical use of ISBN numbers :-)
An eISBN is just an ISBN, though. It may be useful to refer to FRBR in this case. The electronic and print copies are probably the same expressions of the work, but they are different manifestations (and so each has a unique ISBN & it is sloppy to use both).
Refbase, more or less, stores information about specific items (e.g. we have a location for items & allow duplicate records to refer to different copies of the same manifestation).
In this model, it makes sense for refbase to store information about the specific item & the manifestation it comes from, but I don't know if it makes sense for us to store much information about OTHER manifestations of an expression in the same record.
We don't, for example, store multiple editions of a work under the same record.