From the NPS park page:
"Finally yielding to Arnold's wish, Gates ordered out Morgan's rifle men, supported by Dearborn's light infantry, to reconnoiter the position of the enemy."
Supported is not subordinate.
"Moving northward along the road from Fort Neilson Morgan divided his forces in an effort to locate the enemy."
So they were divided early on.
"The first volley all but wiped out the British picket. Rushing forward in hot pursuit of the few survivors, the detachment ran head-on into the main body of Burgoyne's center column only to be driven back in turn and widely scattered. By persistent use of his turkey call signal, however, Morgan was able to rally his men and prepare for the second phase of the engagement."
So Morgan was wandering around the field tooting his turkey call, not giving commands to Dearborn, who was off on a ridge behind the action.
"Aided by the arrival of the regiments of Colonels Cilley and Scammel from Poor's brigade, he re-formed his line in the woods along the southern edge of the 15-acre clearing"
Which is not wear Dearborn was. Interesting Dearborn's background, and relationship to Cilley and his troops:
"In September, 1777, Dearborn was transferred to the 1st New Hampshire Regiment, under Colonel Joseph Cilley. He took part in the Saratoga campaign against Burgoyne at Freeman's Farm. The first battle was largely fought by troops from New Hampshire, Dearborn's home state. The New Hampshire brigade under General Poor and a detachment of infantry under Major Dearborn, numbering about three hundred, along with detachments of other militia, and Whitcomb's Rangers, co-operated with Morgan in the re pulse of Fraser's attack.["
So Dearborn was more familiar with Cilley than he was Morgan.
"The cautious General Horatio Gates reluctantly ordered a reconnaissance force consisting of Daniel Morgan's Provisional Rifle Corps and Dearborn's light infantry to scout out the Bemis Heights area."
Note the author does not say Gate ordered Morgan's command of two battalions out, which ties into the NPS statement above, which says he ordered Morgan out with Dearborn in support. It would seem in the first battle they two did not particularly cooperate or communicate, something Schnitzer notes was rectified in the battle of Bemis Heights the next month.