Respect file permission

$ ls -l test1.png
-rw-------. 1 finn finn 278088 Sep 14 04:12 test1.png

$ mat2 test1.png
$ ls -l test1*
-rw-r--r--. 1 finn finn 278091 Sep 14 04:14 test1.cleaned.png
-rw-------. 1 finn finn 278088 Sep 14 04:12 test1.png

Is it expected behavior? Shouldn't test1.cleaned.png also have same file permission as test1.png (i.e. 600 instead of 644)?