Hello Bitcointalk Community,
i wondered if it is possible to do an ICO and an IEO at the same time.
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There is no need to do that. You should choose one that will be more effective for your project, depending on your feasibility study.
These days, most projects prefer IEO, but I will suggest you do that on a good exchange, in order to attract investors.
Although it's possible but likewise better to focus with the one which really can help you to develop your projects, the demands of starting with IEO's from big well known exchange already getting it's way for more investors to support projects, you need to make a concrete plans to bring something with all investors to trust your projects and support you when you begin talking with the exchange, it's not a small money but if you are serious with your projects you must be willing to do the first move with your own expense.