Two-character homonyms with same meaning This is question about synonymous homonyms in Chinese, in particular, two-character words with same sound, tone. Edit: to keep the question simple and broad, I am using the word "homonym" in a non-technical way and the requirement of same-tone is dispensable. 

I wonder if the immense number of Chinese speakers and limited number of sounds/tones frequently leads to the formation of synonyms based on a speaker's misapprehension of the origin of a word. For example: 

邮轮 and 游轮.

They both are defined in some dictionaries (for example the Yabla on-line dictionary, in which the second occurs in the phrase 'Royal Caribbean Cruise Lines' ) as "cruise liner" or "ocean liner." I suspect that, while an educated speaker would have an opinion about most of these occurrences, it's basically an unavoidable consequence of the structure of the language. 

A similar pressure exists in English, for example, to simplify spelling.

It seems likely to me that this has been the subject of a lot of discussion somewhere and I wonder if someone knows of a paper or article on the subject? 
Of course comments/answers also welcome. 

Also if there are other examples of this situation that would interest me too. Thanks.    

Another example, in case this is not clear: 

From the song "No House No Car,"

保养, "to take care of,"

in the subtitles given as 

包养

In this example I relaxed the requirement of same-tone, as the two first characters do not bear the same tone. And the following: 

浇注, "to cast [metal]" and 

浇铸, same tones same meaning, more or less.
We call these words "异形词" in Chinese.

Definition from Wikipedia:

异形词，是指在普通话书面语中并存并用的同音（指声母、韵母和声调完全相同）、同义（指理性意义、色彩意义和语法意义完全相同）而书写形式不同的词语。例如：“笔画”和“笔划”、“按语”和“案语”、“唯一”和“惟一”等等。实际的使用当中，除了书写的差异之外，它们还有使用频率的不同，但是一般不会造成误解。

中华人民共和国教育部和国家语言文字工作委员会2002年3月31日发布试行了《第一批异形词整理表》。

在繁体中文里面，异形词现象也是存在的。而汉字简化并没有完全消除这些现象，所以从繁体中文中继承也是异形词的主要来源之一。

Here's a link for 《第一批异形词整理表》: 
http://www.edu.cn/20011228/3015609.shtml

And there is 《264组异形词整理表（草案）》 as a supplement : http://dwz.cn/FR5gW

To look for papers on this subject, just search "异性词" on google scholar or other databases and you can find plenty: