(React.JS)Youtube Api nextpagetoken intermittent return duplicated video

Question

when I use "GET https://www.googleapis.com/youtube/v3/search" with nextpagetoken,

intermittent return duplicate video

for instance,

maxResult:5

first call(without nextpagetoken)

get {videoID : a} , {videoID : b} , {videoID : c} , {videoID : d} , {videoID : e}

and than

second call (with nextpagetoken)

get {videoID : d} , {videoID : f} , {videoID : g} , {videoID : h} , {videoID : i}

I expect {videoID : f} , {videoID : g} , {videoID : h} , {videoID : i} , {videoID : j}

this is the problem!!

I wanted the list to constructed like [a,b,c,d,e,f,g,h,i,j]

but

list constructed like [a,b,c,d,e,d,f,g,h,i]

At first I thought a problem comes up when I set called api data on List.

but duplicate data has been called! and already duplicate data on List.

and also This problem does not always occur, but it often happens.

Am I write something wrong code to cause this problem(intermittent return duplicate result)?

Thanks to read long and rough question.