Compare regression coefficients within one sample

I run two univariate linear regressions within one sample (same subjects, two different conditions). Now I would like to know how to compare the regression coefficients in order to find out whether they differ significantly. All of the methods I find apply to a case with two different independent samples. Is there any way to do this in SPSS?

I'm assuming here that the 2 different conditions are the DV.

You can't compare the beta scores directly, but a work-around would be to proportionalize the beta scores within each of your two models, and then see if they are different from one another between the two models.

In terms of making a statistical comparisons between the proportionalized beta scores, the only thing I can think of is to use a bootstrapping technique to run each of the two models multiple times, save the beta coefficients as cases and proportionalize them, and then run a t-test to determine whether the proportions are significantly different.