Is mapping from simplified to traditional characters injective (one-to-one function)? There is a plethora of online simplified to traditional characters converter like this one: https://www.chinese-tools.com/tools/converter-simptrad.html

Is it safe to use them? Won't it cause any mistakes in "translation"? My question boiles down to:

Is the mapping between traditional and simplified characters a one-to-one function? That is, does every simplified character only one traditional character equivalent? 

If not, could you list the most prominent examples?
One simplified character may mapping to multiple traditional ones:


皇后 -> 皇后，後天 -> 后天
頭髮 -> 头发，發財 -> 发财


As reversed, one traditional character may mapping to multiple simplified ones too:


乾燥 -> 干燥，乾隆 -> 乾隆
瞭望 -> 瞭望，瞭解 -> 了解


This wikipedia article had discussed such thing for further reading: https://en.wikipedia.org/wiki/Ambiguities_in_Chinese_character_simplification