How is a bug proposed?

I haven't done any development work in recent days, and I have been modifying bugs. when I took over the project some days ago, the fifth phase of the project was almost done, from the first phase three years ago to the fourth phase six months ago, this project has been used for so long, and each phase is modified on the original basis or added with new functions, the fifth phase mainly involves adding new functions and improving previous functions.
At the time of taking over, this project changed to new employees, and testers also changed to new employees. in this process, I found that the bugs proposed by the testers are very nonstandard. They proposed this: a bug in a page is raised. If there are many functions on this page, this may be raised by two or several testers, so that a page may have many bugs, and they may have raised UI issues, in this way, many bugs are repeated. I have found many similar problems over the past few days. Sometimes, the bugs assigned to myself have been modified, most of these bugs are problems in the past few periods, so it is inconvenient to change. In addition, this problem makes the project very effort-consuming. I don't know how other cnblog friends are working on these issues. I 'd like to ask you some questions. If there is a good way to tell me, in this way, I will tell the test staff that the efficiency will be improved.
In the recent period, I found that in project development, function implementation only takes a very small part of the time, and may not take a long time to test, many friends who have just come out of school pay more attention to the implementation of actual functions and think that the function is almost implemented. In fact, it will take a lot of time to modify bugs, however, there are few bugs in writing highly. haha