Meaning of 那就一样来一个吧 in the conversation
那就一样来一个吧 is a shortened sentence. In day to day speech, it is a common practice to omit some elements that are presumed to be understood or strongly implied.
You can understand the sentence as &quot;那就(每)一样(种类)(都給我)(各)来一个吧 &quot; --&gt; &quot;Then bring me one each from each kind&quot;

&quot;每一样&quot; (each kind ) refers to 辣子鸡丁 and 糖醋鱼 which are the two kinds of dishes mentioned in the previous sentence, therefore, no need to repeat them in the next sentence. If three kinds of dishes were mentioned, then 每一样 (each kind) would refer to all three

&quot;給我来一个XX&quot; = &quot;bring me a XX&quot;


A detailed sentence would be: &quot;那就給我辣子鸡丁和糖醋鱼各一个吧&quot; (Then give me spicy chicken and sweet and sour fish one dish each)
Similarly:
&quot;那就每样給我来两个吧&quot; would mean &quot;Then give me spicy chicken and sweet and sour fish two dishes each&quot;
Note: Shorten 那就(每一样)来一个吧  to 那就(每样)来一个吧 is more clear than 那就(一样)来一个吧 because '一样' might be interpreted as &quot;the same&quot;
The above answer is based on Standaed Written Chinese (SWC)