Can the same file submitted for Fixed Layout eBook conversion also be used for dynamic (flowable) layout conversion? Not likely. Almost all PDFs designed for fixed layout conversions are not suitable for dynamic (flowable) conversions.
Related articles What files do I need to supply for you to create a Fixed Layout eBook file? How much does it cost to convert a Fixed Layout eBook? Will my dynamic eBook look like my print book? What are Fixed Layout eBook files? How is Fixed Layout different from a PDF?