Is it OK to use 只 (only) when it already uses 只 as a measure word? In the following sentence:


  ”银座养蜂项目“始于2006年，目前在银座的三个大厦屋顶都设有养蜂场，各有20-30万只蜜蜂。


The sentence means:


  "Ginza Bees Project" started in 2016. Now the roof of all three buildings in Ginza have the bees farms, and each has 200 to 300 thousands of bees.


In this sentence, the 只 is a measure word for 蜂蜜. 

However, if you want to express it as "each has only 200 to 300 thousands of bees", can you still use 只? Or should you use a different word to express "only" in order to avoid the duplicate of 只 (or possibly the confusion as well)?

In this case, how should the whole sentence be if you add "only" in the sentence?
"只有20-30万只蜜蜂" is a valid sentence in simplified Chinese. You just have to read the two 只 differently, because they have different meanings.


The first "只" in the sentence means "only" in both simplified and traditional Chinese and it is read as /zhi3/.  (It can also be written as "祇" in traditional Chinese) 
The second "只" in the sentence, is the simplified version of 隻 (classifier for certain animals) and it is read as /zhi1/


The sentence "只有20-30万只蜜蜂" is actually "祇有20-30萬隻蜜蜂" in traditional Chinese characters.