help,Key conflict of xbox controllers

hello,every one。 when I use retroarch on iPhone,the newest version。and my controller is xbox controller。 when I input L1+START,together press down.then the input will become l1+select. when I test this,i keep retropad on the screen,so I can see which keys are pressed down。 so I can’t use the combo hotkey “l1+r1+start+select”,it’s not working. but,when,I use retroarch on my android tv,the same controller,There won’t be the same problem occurring,everything is ok。 plese help me,thank you every body,sorry for my poor English。