There are a couple good academic sources that touch on this topic:

• Dever, W. G. (2005). Did God have a wife?: Archaeology and folk religion in ancient Israel. Grand Rapids, Mich: W.B. Eerdmans Pub. Co.

• Cross, F. M. (1973). Canaanite myth and Hebrew epic: Essays in the history of the religion of Israel. Cambridge, Mass: Harvard University Pres

• Walton, J. H. (2006). Ancient Near Eastern thought and the Old Testament: Introducing the conceptual world of the Hebrew Bible. Grand Rapids, MI: Baker Academic.

The answer is that it's a very complicated question. We don't have good texts from the earliest days of Hebrew religion. It does appear from the archaeological evidence that there was a significant number of instances of multiple deities being worshipped in that part of the world. We have recovered many figurines of Astarte or Asherah from the Holy Land.

In addition, there are a number of arguments from text-critical analysis of a conflation of two deities, El and Yahweh. In addition, there are a couple inscriptions, one at a cultic site now called Kuntillet 'Ajrud and one at Khirbet el-Qom which mention "Yahweh and his Asherah".

What we don't have is a set of doctrinal statements or religious dogma that outlines the canonical beliefs of this time period. What probably occurred was much more syncretic than modern rabbis wish for. There was almost certainly a lot of "following of other gods", and syncretism integrating other beliefs and other deities into the Hebrew religion.