How to disable if same file is uploaded?

Question

I need to input 3 files at the same time,
I'm wondering how NOT TO insert if the same file is uploaded at the same time. It is okay if its already in the db.
Example is already inserted in "warm_up" then the other input (drill1 and drill2) wont be able to upload file已经插入“warm_up”然后其他输入（drill1 和drill2）将无法上传文件
I'm also thinking if it is possible if the file I inserted any on the "input file" won't show on the other inputs.

<input type="file" name="warm_up"  required/>                       
<input type="file" name="drill1"  required /> 
<input type="file" name="drill2"  required />

Answer 1

php发送表单后可以比较文件名和扩展名的大小