EMB-170/175 Technician reported while accomplishing oil service to both engines; they did not remember securing the oil cap or oil door on the #2 engine.

Narrative

I was called over the radio to do oil service on a plane that was located at the hangar. Once I arrived to the aircraft at the hangar; I proceeded to service both Engines with oil. Servicing number one Engine with 3 QT and Engine two with 2 QT. I started by placing 5 quarts of oil on the gear door over the #1 and #2 MLG tires; I opened the three oil cans with my Leatherman then pouring one quart into the # 1 Engine. I then proceeded to take two quarts of oil to the #2 Engine. opening each can with my Leatherman and pouring one quart into the #2 Engine. I then proceeded back to the number one Engine and continuing the steps until i filled the #1 Engine with 3 QT and the #2 Engine with 2 QT. after I finished filling #1 Engine with 3 QT I secured the oil cap and closed the oil door securing the oil door with the four screws. once I completed Servicing #2 Engine with 2 QT I remember taking the oil cans back to the truck but I do not remember Securing the oil cap or the Oil door. Cause: I returned the 2 empty quarts of oil to the truck without securing the oil cap or oil door on the # 2 Engine.Suggestions: Best way I feel to prevent this from happening is to double and triple check before signing off any work done and before leaving the area.