Do you mean to say that you think there is an easier solution? I guess that depends on your definition of easy. How about a state machine in an FPGA. Would that be easier? Maybe a discrete implementation of a state machine, say 5 or 6 MSI chips. Would that be easier? How about some relay ladder logic. Would that be easier?
How about a definition of easy, before we go spending alot of time proposing solutions that don't meet your requirements.
What you'd like to build is not terribly difficult. Depending on what you want the device to do after it detects the light and also as a matter of design the lighting in the environment it will operate in (daytime brightness and different angles of light may present a small challenge, those lights are usually a pretty dim red LED also) there are a few routes you could go. Using a microprocessor, a small breadboard and a few components you should be able to make it work. If you can ask a slightly more specific question I might be able to give you a better answer. Is this going to be used for something important or are you just messing around?
Ubergeek63, how is a 4017 and oscillator going to help? If I've read the requirement correctly, the OP wanted to detect a double flash sequence, not generate one. What the OP needs is a negative edge triggered one-shot that activates an AND gate which lets the 2nd pulse through to trip a D type flip-flop.
Yes, a PIC, AVR, etc would make the whole job easier. Using a small 10F or 12F series PIC is the way I would do it. But it wouldn't be the easy way for someone with no microcontroller experience.
I like Ubergeek's suggestion, if the light pulses clocked a 4017 then it would work. The zero output would hold a timer in reset, output 2 would trigger the relay and the (2 second) timer output would reset the 4017. If two pulses arrive within 2 seconds then output 2 would go high and trigger the relay.
how about charging a capacitor via a resistor and diode. if you use the correct values one pulse would charge it to 6v and the second would get it up to about 12, and a 12v relay could pull in