That's a good question.
My opinion build a strong network and establish whom would provide quality advice for specific area you want to build on.
Report Divine's answer
If you have one venture, then get one or get more mentors to learn on a larger scale. However, human needs are insatiable, just so you know, you might need to get many mentors and allocate them for one venture or the other as the case may be.
Report Tim's answer
Depends upon quality of mentor [their experience and knowledge base] and your ability to trust&learn
Report Reshma's answer
Yes -- it is fine to have more than one mentor at a time. Especially when you are seeking help regarding different expertises, more than one mentor can be a great help.