Kindle Fire(4th Gen) Issue - SendKeys function types a pin number in 2 adjacent boxes at same time

Android mobile automation using appium with Java and Kindle Fire (4th Gen) device. The Kindle fire app have a page with 3 different input text boxes adjacent to each other. I need to enter randomly generated pin numbers in each box. The pin values are determined by the text pattern provided e.g. enter 2nd, 1st and 3rd character of your pin. Respective pin for each character is captured and should be entered in the Kindle text input boxes sequentially.

However, using Appium sendKeys function, each sendkeys entry is entered in two boxes at the same time (ie box 1 and 2), which is very weird. Each character entry is duplicated in the next box. This sequence repeat itself for every character entry for the 3 boxes.

I have tried many things but no solution, please i will appreciate if anyone could help. This problem also happens in Mashmallow device.