Reproduction steps:
1) Open user's attached project
2) Build and run "Entry" scene on any Android device
3) Touch screen with 3 - 4 fingers around the button
-- Notice that with each touch Input.touchCount and touches.Lenght are updated and new sprites are added on the touch positions
4) While holding with few fingers screen touched, release one finger and touch button in the middle of screen
5) Release remaining fingers
-- Notice that Input.touchCount and touches.Length are not 0 or 1 (if one finger is touching screen); Sprites which are being drawn on touch positions are still drawn

Expected result:
All values related to multitouch should be set to 0 or limited to be used as there's one touch at a time limit (max value of touches.Length should be 1)

Note: After setting Input.multitouchEnabled to true, Unity still have stored previously recorded touches. To reset those you have to touch the screen with same amount of touches as before.

Reproduced with:
5.3.7p3, 5.4.4f1, 5.5.0p3, 5.6.0b2

DUT:
LG G3, Android 5.0
Samsung Galaxy S7, Android 6.0