While it is true that Hailey Bieber has done and said similar things as Selena Gomez, there is no way to prove that she is intentionally copying Selena Gomez.
The background of the feud between Hailey Bieber and Selena Gomez stems from the fact that Hailey is married to Justin Bieber, who is Selena's ex. Many fans still fantasize about Justin and Selena's relationship, which has made tensions high.
In the video "11 Times Hailey Bieber Copied Selena Gomez", they explain that one of the times Hailey "copied" Selena was by saying the same phrase as her. Selena said that the one thing she wished people could see about her was her heart, and after that, Hailey said the same phrase on The Tonight Show.
There are other examples in this video as well; however, there is no way to prove that Hailey is copying Selena on purpose. These could all be coincidences that cannot be proven factually.