Three years ago I published 2 papers in the open access journals with APC that are indexed in Emerging Sources Citations Index (ESCI), Directory of Open Access Journals (DOAJ) and Scopus. This was according to the university directions to publish fully open access. I have to admit that, three years ago, I was new to the research career and I blindly went by the general guidelines the university has towards publishing. Now, when I am trying for other academic positions, they are increasingly looking for publications in Science Citation Index (SCI) or Science Citation Index Expanded (SCIE) category of journals. In this category, I have only one publication. Moreover, I see that the papers published in ESCI journals, in general, haven't received much attention compared to the ones published in SCI or SCIE. So my question is,
Is it possible to reuse some of the results that I published in ESCI journals and add additional case studies and try to publish in SCI or SCIE journals (with proper acknowledgment to the old paper)? Will this be a good strategy or it is considered as a duplicate publication?
This is more of a general question. If all science has to be published in SCI/SCIE indexed journals, then why do some top reputable publishers promote the ESCI journal category? With the move to fully open access, SCI / SCIE index journals open access fee are very high compared to the open access journals in ESCI category. This is an important factor for some people to choose the ESCI journals. How do the other academicians see this?
Note: The journals that I published are within manufacturing category.