A 25-year-old Anaheim woman, accused of involuntary manslaughter in the July deaths of her 3-month-old twins, has been ordered to stand trial on Feb. 9. Orange County Superior Court Judge Luis A. Cardenas set the trial date as Beverly Jean Ernst formally entered a not-guilty plea to two counts of involuntary manslaughter and two counts of felony child endangerment. Evidence at Ernst's preliminary hearing showed that she and a boyfriend, Scott Morrow, slept for five hours July 20 in a Garden Grove shop where he lived, while the twins were left alone in her car. The children, Adam and Ashley, died of heat stroke. Ernst's attorney, Deputy Public Defender Dennis P. O'Connell, claims that Morrow promised to watch the children while she slept, but ended up falling asleep himself. Judge Cardenas on Monday allowed Ernst to remain free on her own recognizance.