Think about it, Klaus has been the only one able to kill Elena or Katherine even though they looked like his first love. The rest, Elijah, Damon and Stefan, has all on one point been enthralled by their similar looks.
Elijah may have fallen for Katherine, and the Salvatores clearly love Elena, but all of them got interested because they loved another generation first. They started being interested because she looked like the one they loved many years ago. Later they grew to love that person, but it was still the similarity that peeked them.
Meanwhile Klaus is the only one who seems to be able to separate it. A few episodes ago he stated that “love like that never goes away”. So he clearly still loves Tatia deep down. Despite this he loathes Katherine and this didn’t stop him from wanting to kill and torture her and Elena. Because for Klaus it might have been real.
It was Tatia that he loved. Not someone that looked like her, so the doppelganger allure never lured him in like the rest of the boys. He loved one person and just because someone else looked like her, didn’t mean he would fall for her. It wasn’t about her looks. It was about her.