Your arrays hold different data types, maybe this has something to do with it?
On the TX:
const int Arraynum = 2;
int Array[Arraynum];
Meanwhile, on the RX:
byte Array[2];
int variables are of size 2 on Arduino, while byte variables are of size 1. You might be sending more data (4 bytes) than the RX can store on the array (2 bytes), therefore the second value is being "lost".