I am reading a proof and got into following equality $$ e^{-2 \theta T } \int_{0}^T e^{2 \theta t} \left(\left( \int_{0}^{\infty} e^{-\theta s} dWs \right)^2 - \left(\int_0^t e^{-\theta s}dWs \right)^2\right)dt = $$ $$= e^{-2 \Theta T } \int_{0}^{T}e^{2 \theta t}\left( \int_{t}^{\infty}e^{-\theta s }dWs\right)^2 + 2 e^{-2 \Theta T } \int_{0}^{T}e^{2 \theta t}\left(\int_{t}^{\infty} e^{-\theta s}dWs\right)\left(\int_{0}^{t} e^{-\theta s}dWs\right),$$ where $\theta >0$ and $W$ is Wiener process.
I would be expecting only the first term on the right hand side of the equality. Is there any formula that justifies this?