This is what we can read from the Jewish Encyclopedia:
The name Ba'al (), apparently as an equivalent for Yhwh, occurs as an element in a number of compound proper names, such as Jerubbaal, Ishbaal, Meribaal, etc. Some of these names, probably at a time when the name of Baal had fallen into disrepute (comp. Hosea ii. 16, 17), seem to have been changed by the substitution of El or Bosheth for Baal (comp. II Sam. ii. 8, iv. 4, v. 16; I Chron. viii. 33, 34; ix. 39, 40; xiv. 7).
Why did Saul give to one of his sons the name Ishbaal? Ishbaal means "man of Baal". It clearly means that Baal was as God as Yahweh for ancient people in Israel. The monotheistic law given by Moses was unknown for the israelites living before the babylonian captivity. Dishonest scribes of the postexilic age did a historical revisionism, in which they told to the unlearned Jews, the lie that Yahweh was always the one and only the true God of Israel. A lie similar to that of the Watchtower Society, in which Jesus came invisible between 1914 and 1919 so as to inspect all religion organizations, then he declared that the Society is his Channel on Earth.