In the past decade and a half, physical unclonable functions (PUFs) have been introduced as a promising cryptographic primitive for hardware security applications. Since then, the race between proposing new complex PUF architectures and new attack schemes to break their security has been ongoing. Although modeling attacks using conventional machine learning techniques were successful against many PUFs, there are still some delay-based PUF architectures which remain unbroken against such attacks, such as the double arbiter PUFs. These stronger complex PUFs have the potential to be a promising candidate for key generation and authentication applications. This paper presents an in-depth analysis of modeling attack using deep learning (DL) techniques against double arbiter PUFs (DA-PUFs). Unlike more conventional machine learning techniques such as logistic regression and support vector machines, DL results show enhanced prediction accuracy of the attacked PUFs, thus pushing up the boundaries of modeling attacks to break more complex architectures. The attack on 3-1 DAPUFs has improved accuracy of over 86% (compared to previous research achieving a maximum of 76%) and the 4-1 DAPUFs accuracy ranges between 71%-81.5% (compared to previous research of maximum 63%). This research is crucial for analyzing security of existing and future PUF architectures, confirming that as DL computations become more widely accessible, designers will need to hide the PUFs CRP relationship from attackers.