People have more than one-page resume that includes all of their qualifications and experiences but one page resume is the best because recruiters only have three to eight seconds to glance at your resume to conclude that if you are capable for the position and a deserving candidate. All the required keywords and research related experiences should be highlighted in the resume to grab the attention of the recruiters and these things make your resume stronger.
Some people are in the industry for many years and have experience of working with different companies that makes their resume longer.
Double page resume looks cleaner because of the spacing. People having their resume more than two pages that includes an overview of everything they have done in their career and it becomes a CV that is curriculum vitae. Such CVs are also sent to the sponsors and they decide to keep them for the study or not depending upon their qualification.
While sending your resume to the hiring managers, make sure to keep it to the point and clear understanding of everything that is mentioned. But something that is really important to be mentioned and is related to the research work then resume can be stretched to two pages.