https://www.twitch.tv/videos/521090595?t=2h11m47s (orignial VOD, DarkViperAU, thanks to Reloe)
Here are clips from the VOD above:
https://clips.twitch.tv/PeppyBillowingSrirachaRitzMitz (Driving to the mission, first recognition)
https://clips.twitch.tv/HyperResilientStingrayDancingBanana (IAA building cutscene conversation lost, allowing Michael to instantly enter)
There exist more instances, this is not an isolated case. I couldn't find other VODs or make the clips, however.
The script for this mission is called fbi2. Is also seems that the script player_scene_m_fbi2 is used for the scene where Trevor is harrasing the FBI agent. Seems it spawns the helicopter/franklin's bike/FBI vehicle itself?
Cutscene fbi_2_mcs_1 is the one that plays the overlapping/early conversation audio.
In dictionary missfbi2@leadinoutfbi_2_mcs_1:
_leadin_action_trevor: For Trevor, when harrasing the FBI agent.
Dave's ped handle seems to be shared using the shared ped global, described in Mission-Research.md.
This global (and it's members) are specifically used in this script, and in player_scene_m_fbi2, to have shared data between the two. This includes vehicles, peds, blips, and states. It seems like most of these are initialized by player_scene_m_fbi2, and some by fbi2. Below is a list of each global and what it should contain.
0x15D93: Blip.
0x15D93 + 0x1: Int. Have some blips been created yet?
0x15D93 + 0x2: Vehicle (hash 'frogger')
0x15D93 + 0x3: Vehicle.
0x15D93 + 0x4: Vehicle (hash 'utillitruck3')
0x15D93 + 0x5: Vehicle (hash 'utillitruck2')
0x15D93 + 0x6: Vehicle (hash 'fbi2')
0x15D93 + 0x9: Ped (hash 'cs_fbisuit_01'). FBI agent Trevor harasses?
0x15D93 + 0xA: Int. Have the shared entities been created yet?