how does address.sol and safemath.sol return the same bytecode?

[eladalkabets2603]

SafeMath.txt
Address.txt

(.sol extension isnt supported)
i recently used your remixd for testing one of my project , where i copied sol files using chain explorers devided them into sub contract , added the imports and compiled them to get the byte code.
while testing the code i ran into something odd (in my opinion)
both safemath.sol and address.sol (from the sushi token on 0x6B3595068778DD592e39A122f4f5a5cF09C90fE2 ethereum mainnet)
how are both of these files return the same byte code?