Both phrases can be used to express your desired phrase but the second also acts an idiom which can apply to other similar situations.
For example, if a lion tamer had to feed a lion as part of his daily work, it would seem strange to someone who isn't a lion tamer, but he may say "Oh well, it's just another day at the office".
It can be used as an expression that it is something a person is used to and it happens all the time.
どちらの表現を使っても言いたいことを表現することが出来ます。
ですが、二番目の表現はイディオムで他の同じような状況でも使うことが出来ます.
例えば、ライオン使いが毎日の仕事でライオンに餌をやります。
これはライオン使いではない人にしてみたら変わった事ですが、ライオン使いにとって見たら日常的な事ですよね。
そして、彼は言います。
"Oh well, it's just another day at the office".
（ああ、いつものことだよ）
これはある人にとって珍しくもない変わらない日々の事を表す表現です。
Same old, same old' and 'same old story' are both popular phrases that mean you have done the same routine as you usually do, and nothing much has changed since the last time they asked you.
'Another day. another dollar' is an American English phrase, that is also used in the UK, to describe going to work as usual as part of your normal routine. It is usually said at the end of the working day.
Same old, same old' と 'same old story'はいつもしているように、また前回聞かれたときと何も変わらない同じルーティーンを繰り返していると意味する一般的な表現です。
'Another day. another dollar'はアメリカ英語ですがイギリスでも使われ、 通常のルーティーンの一部として仕事へ行くことを表現します。勤務日の最後によく言われる言葉です。
I went to work as usual, and did my work as usual.
I went to the office and did the same, usual work.
I did the same work I always do, and did the same work I always do.
「普段通り会社に行って普段通り仕事をした」は英語に訳すとこのようです。
I went to work as usual, and did my work as usual.
I went to the office and did the same, usual work.
I did the same work I always do, and did the same work I always do.
投稿者さんが書いた英語はが近いですが、少しスペルが間違っていました。
こちらは正しい： Nothing special, I went to the office and did my usual work.
specil X→ special
useally X → usual, usually
例文
A: How was your day?
A: 今日はどのような１日過ごしたの？
B; It was nothing special. I went to the office as usual, and just did the same work I always do.
B; 大したことじゃなかった。普通通りオフィスに行って普通通り仕事をした。
ご参考までに。
Same old same old - we use this expression when we want to express that we are a little bored with the same regular routine every day, repeating itself endlessly..... This expression is .used to convey that something is drearily predictable or familiar.
"The game's fantasy setting is the same old, same old."
Just another..... - this expression again means that the present or discussed 'one' is the same as many presious 'ones.'
Same old same old - 毎日終わりのない同じことの繰り返しの日課に少し退屈さを感じているときに使う表現です。この表現は、何かがありきたりで、よく知っているということを言うのに使われます。
"The game's fantasy setting is the same old, same old."
そのゲームのファンタジー設定はありきたりだ。
Just another..... - これも、ありふれた、ありきたりのという意味です。
If you do something as 'normal' or 'usual' it is something you normally do so nothing different we have an informal saying for this 'same old same old' meaning to do the same thing
do something as normal/usual'は「いつものように～する」という意味です。
英語にはこれについてのインフォーマルな決まり文句があります、'same old same old'。これは「いつもと同じことをする」という意味です。
The three sentences you see provided above are excellent ways to express to your listener that you had a usual working day. In the third sentence you will see the term run of the mill. This means normal or nothing out of the ordinary. This term is appropriate for informal settings, like talking with close friends or family.
上記三つの例文は、いつもと同じように仕事をしたことを伝える素晴らしい言い方です。
三つ目の例文には "run of the mill" という表現が使われています。これは「普通の」「代わり映えのしない」という意味です。この表現は家族や親しい友人と話すときなどインフォーマルな場面に適しています。
"I had a standard day at work, nothing unusual happened"
In order to explain that you went to work and did work as usual, you could simply state "I went to work as usual and did work as usual" or "I had a standard day at work, nothing unusual happened". Both these sentences explain that you have done nothing that you wouldn't normally do and as a result have had a day which is considered very normal for you.
「いつも通り会社に行っていつも通り仕事をした」は、次のように言えます。
"I went to work as usual and did work as usual"
（いつも通り会社に行っていつも通り仕事をしました）
"I had a standard day at work, nothing unusual happened"
（会社ではいつも通りの日でした。特別なことは何もありませんでした）
どちらの文も、いつもと違うことはなく普段通りの日だったと伝えています。
イギリス 
アメリカ合衆国 
