Is it possible to know whether a particular value is the result of ECadd or ECdouble?
No. I assume "value" is as expressed in a public key; and parameters with a generator of prime order, as is the case for secp256k1 of the question.
For a start, every valid public key $R$ can be obtained by adding two valid public keys $U=2R$ and $V=-R$, or doubling a valid public key $W=((n+1)/2)\,R$ where $n$ is the (odd prime) order of the generator.
And even if we change the question to: when computing public key $R$ from secret private key $r$ with $0<r<n$ as $R=r\,G$ by scanning the binary representation of secret key $r$ from most to least significant bit and using the double and (conditionally) add method, we can't tell from $R$ if it was obtained by doubling or adding, that is if $r$ is even or odd. Argument: if hypothetically we could do this, we could find $r_i=r\bmod2^i$ for incremental values of $i$ by constructing public keys $R_i$ derived from $R$ and earlier results that would ultimately reveal $r$. If the hypothetical method always work, $R_i=(2^{-i}\bmod n)(R-r_i\,G)$ does the trick, and this can be adapted for hypothetical method giving only a small advantage for random $R$.
