Not really...
Let us imagine that file1 contains:

Code:

A1 x
A1 y
A1 z

and that file2 contains:

Code:

A1 B2 C3

and that file3 contains:

Code:

A1 x
B2 y
C3 z
A1 a
B2 b
C3 c

In this example, files file2 and file3 both contain all three strings, but the output from:

Code:

grep -E 'A1|B2|C3' file[1-3] | sort -u | cut -d: -f1 | uniq -c

is:

Code:

   3 file1
   1 file2
   6 file3

which shows that only file1 comes up with a count of three unique matching lines.

Until we get a clear description of the desired output and the log file format, I think we're wasting our time guessing at what might supply the output the OP really wants.