Do I need a double-entry visa for Guangzhou - Macau – Guangzhou Tour

Yes, you need a double-entry visa for Guangzhou - Macau - Guangzhou trip. 

♦ Let me clear the idea:
Firstly, you can to Guangzhou from you country. During this time, you need to use visa to enter into Guangzhou.

And then, you go to Macau from Guangzhou. During this time, no need to use your visa.
 

And then, you will come back Guangzhou from Macau. During this time, you need to show visa to the customs.

So in total, there are two times you need to use in this trip. So you need a double-entry visa if you 
► Firstly come to China mainland city from your country, visa needed

► And then back to China mainland cities from both Hong Kong and Macau, visa needed