The advent of decentralized digital currencies, notably exemplified by cryptocurrencies like Bitcoin, has ushered in a new era of financial transactions, promising secure and trustless exchanges without the need for intermediaries. However, this transformative technology has also introduced novel security challenges, with double spending attacks being one of the most critical concerns. This study delves into the phenomenon of double spending attacks within decentralized digital currencies, analyzing the underlying mechanisms, vulnerabilities, and the potential repercussions on the integrity of digital financial systems., This research identifies the various strategies employed by attackers to execute double spending attacks and investigates the economic incentives and technical prerequisites that enable such attacks to succeed in different consensus mechanisms. In response to these challenges, the study also explores a range of countermeasures and mitigation strategies that have been proposed to safeguard against double spending attacks. These countermeasures encompass advancements in consensus protocols, cryptographic techniques, network monitoring, and transaction validation procedures. The research sheds light on the evolving nature of double spending attacks and highlights the importance of proactive measures to ensure the security and robustness of decentralized financial systems. By gaining a deeper understanding of these challenges and countermeasures, stakeholders, including developers, regulators, and users, can make informed decisions to enhance the overall resilience of decentralized digital currencies against double spending attacks.