Fix 'Duplicate Code' issue in Net\MicroCoinClient.cs

It's currently on:
[Net\MicroCoinClient.cs:243-255
](https://www.codefactor.io/repository/github/microcoinhu/microcoincore/source/master/Net/MicroCoinClient.cs#L243)[Net\MicroCoinClient.cs:162-174
](https://www.codefactor.io/repository/github/microcoinhu/microcoincore/source/master/Net/MicroCoinClient.cs#L162)